THE UNIVERSITY OF KANSAS

PALEONTOLOGICAL CONTRIBUTIONS

November 12, 1976 Paper 86

LAMELLORTHOCERATIDS (CEPHALOPODA,ORTHOCEROIDEA) FROM THE LOWER

DEVONIAN OF NEW YORK'

GEORGE D. STANLEY, JR., and CURT TEICHERT

University iit Ka usas. Lawrence, Kansas

ABSTRACT

Devonian lamellorthoceratid cephalopods from North America are described in detail

for the first time. They occur in the Esopus Shale of Emsian age of New York State and

are here named Esopocems sinuosum, gen. et sp. nov. They are straight, slowly expanding

orthoconic forms characterized by cameral deposits in the form of sinuous, radiating lamel-

lae, disposed in a unique geometric pattern. These internal lamellae fill all the chambers

of the phragmocone of the holotype but appear to be absent from the body chamber. hi

cross section, these cephalopods bear some superficial resemblance to rugose corals.

The new species shows considerable variation in internal and external morphologic

characters, which may be attributed to mode of preservation as well as to presence of differ-

ent growth stages. Esopoceras resembles all of the four previously named genera com-

prising the family Lamellorthoceratidae, occurring in Europe, North Africa, Turkey, and

the Urals, but it is most similar to the genus Lamellorthoceras (Termier and Termier,

1950). The existence of Esoroceras in North America greatly extends the geographic range

of this short-lived and as yet little-known group of cephalopods.

INTRODUCTION AND ACKNOWLEDGMENTS

The family Lamellorthoceratidae is composed

of a small group of genera having orthoconic

shells characterized by cameral deposits in the

form of more or less closely set, radiating lamellae

spaced between successive septa, either vertically

Manuscript received April 13, 1976; revised manuscript receivedMay 19, 1976.

or at various angles. Until recently members of

this family were known only from rocks of

Early and Middle Devonian (Siegenian to Con-

vinian) age of Europe (France, Germany, Ural

Mountains), Turkey, and North Africa.

2The University of Kansas Paleontological Contributions—Paper 86

In April, 1974, Mrs. Judith Rehmer Hepburn,Clark University, Worcester, Massachusetts, sentCurt Teichert a small collection of orthoconiccephalopods, which she had correctly identified asbelonging to the family Lamellorthoceratidae.They were derived from the middle member ofthe Esopus Formation of Emsian age in a quarrynear Rosendale in southern New York State.

After the manuscript of this paper had beenalmost completed we learned from Dr. R. H.Flower, New Mexico Bureau of Mines and Min-eral Resources, that for some time he had had inhis possession a collection of fossils made byStephen Mellendorf, apparently from the samelocality as Mrs. Hepburn's collection, and whichalso included representatives of Lamellortho-

ceratidae. A preliminary note on this occurrenceis under preparation by Flower and Mellendorf.

We are greatly indebted to Mrs. Hepburn forallowing us to describe this interesting and un-usual group of orthocerid cephalopods, and weare grateful to Dr. Flower for a copy of his jointmanuscript with Mellendorf. We are also in-debted to Dr. Flower for bringing to our atten-tion the paper by Howell (1942). Michael Fred-erick prepared the photographs of all New Yorkspecimens on Plates 1 and 2, and Roger B. Wil-liams skillfully drafted the text-figures.

G. D. Stanley acknowledges support by theWallace E. Pratt Research Fund at the Universityof Kansas. The Department of Geology atPrinceton University generously loaned us thespecimens illustrated by Howell (1942).

DISTRIBUTION AND CHARACTERS OF LAMELLORTHOCERATIDAE

The family Lamellorthoceratidae was erectedby Teichert (1961) to include ArthrophyllumBeyrich and Lamellorthoceras Termier and Ter-mier, two genera of straight to slightly endo-gastric orthocerid cephalopods characterized byradiating cameral lamellae that, in some forms,almost completely fill the camerae of the phrag-mocone. In the Treatise on Invertebrate Paleon-tology, Sweet (in Teichert et al., 1964) includedin this family three genera, Lamellorthoceras,Arthrophyllum, and Gorgonoceras Zhuravleva.A fourth genus, Coralloceras Zhuravleva, con-sidered by Sweet (in Teichert et al., 1964, p.K234) to be synonymous with Lamellorthoceras,is regarded as a valid genus by us. The radiatingcameral lamellae that characterize the membersof this family superficially resemble the septa ofrugose corals, and it is due to this remarkableconvergence that Beyrich (in Carnal!, Ewald, andRoth, 1850) named the first lamellorthoceratidArthrophyllum, believing it to be a coral. Asimilar erroneous assignment of another lamellor-thoceratid YaS iater made by E. C. Stumm (inHowell, 1942; see below).

Almost all of the literature on this uniquegroup of cephalopods is found in German, French,

and Russian publications. Of the four genera,Arthrophyllum occurs in Germany, Gorgonocerasin the Ural Mountains, Coralloceras in NorthAfrica (Morocco, Algeria), and Lamellorthocerasin North Africa (Morocco, Algeria), Germany,France, and Turkey. Esopoceras sinuosum Stan-ley and Teichert, gen. et sp. nov., described in thispaper, is from New York, and this discovery ex-tends the range of this family to include easternNorth America. The geologic range of Lamellor-thoceratidae is relatively restricted within theDevonian, the family occurring in the Siegenian,Emsian, and Couvinian stages (upper Lower tolower Middle Devonian).

Except Gorgonoceras, which appears to bemore distinct, the four genera share many char-acteristics, particularly in regard to the cameraldeposits. Babin (1964) has already pointed outthese similarities. Based on published descrip-tions and photographs available to us, we haveassembled in Table 1 a comparison of the char-acters of the four previously described generawith those of the new genus Esopoceras, describedherein.

The cameral lamellae that characterize thefamily vary in two respects: their configuration

Stanley &Teichert—Lamellorthoceratids from Lower Devonian of New York

3

TABLE 1. Comparisons of Genera of Lamellorthoceratidae.

conch

ornament

sutures

posteriorfissure

apical angle

septa

Length/Widthratio of cameraecameraldeposits

Art hrophyllum

laterallycompressed

?transversecrenulations

straight

present

Moderate(8-13°)

slightly concave

1:6-1:4

episcptal only,nearly straight

Coralloceras

dorsoventrallydepressed

straight-oblique

distinct

large (15-24°)

moderately concave1:4-1:3

episeptal only,?nearly straight

straight-sl.oblique

abent

small (4°)

strongly concave

1:1-1:1.5

epi- and hypo-septal; nearlystraight toundulating

?straight

Couvinian

Urals

undulating

present

moderate (9-12°)

strongly concave

1:3-1:2

epi- and hyposeptal;nearly straight toundulating andcurved

slightly sinuous,converge alongtransverse axisSiegenian-Couvinian

North Africa, Ger-many, Turkey, France

circular andlaterally compressed

Longitudinal costulesand smooth transverseannulationsundulating

?present

small (4-5°)

strongly concave

1 :3-1 :2

epi- and hyposeptal,nearly straight tohighly undulatingand slightly tostrongly folded

slightly to highlysinuous, convergealong transverse axisEmsian

New York

Gorgonocrras Lamellorthoceras

Esopoccras

circular circular

longitudinal ?fine, transverse-costules oblique striae

geometry of straight to straight toexternal edges slightly sinuous slightly sinuousof lamellae

Age Emsian- Einsian-Couvinian

Couvinian

Occurrence Germany North Africa

in the camerae as they converge from the walltoward the siphuncle, and the shape of theirexternal edges, which are in contact with theshell wall. The latter are apparent on steinkernsand are only an outward expression of the internalarrangement of the lamellae. The disposition andarrangement of the lamellae is a useful taxonomiccharacter. Often, characters such as the position

of the siphuncle, apical angle, length/width ratioof chambers, and ornament are either too variableor difficult to ascertain due to poor preservation.Specimens that occur in dark shales are fre-quently crushed and replaced with iron sulfidethat then converts to limonite, thus destroyingmost of the wall structures as well as obscuringthe internal structures.

PRESENT INVESTIGATIONS

Mrs. Judith Rehmer Hepburn made availableto us a collection of about 13 specimens of straightcephalopods, which we describe here as Esopocerassinuosum Stanley and Teichert, n. gen., n. sp.This collection came from the upper part of themiddle member of the Esopus Formation (seeFenner, 1971, p. 16) at a quarry 1.2 kin west ofCottekill, northwest of Rosendale, New York(Fig. 1). Cephalopods are restricted to the upperpart of the middle member, which here consists

of uniform, homogeneous, dark, cherty, siltyshale with clay and ironstone concretions. In ad-dition to cephalopods the beds contain abundantbrachiopods, rare gastropods, trace fossils, andplant remains (Judith Rehmer Hepburn, writtencommun., August, 1975).

The fossiliferous unit that contains the cepha-lopod fauna is 4.5 m thick. All cephalopods ex-amined by us have orthoconic shells and are moreor less fragmentary. This unit also contains other

4

The University of Kansas Paleontological Contributions—Paper 86

FIG. I. Index map showing location of quarry in Esopus Formation from which Esopoceras sinuosum Stanley andTeichert, n. gen., n. sp., was obtained.

orthoconic cephalopods, the majority of whichare either crushed or entirely flattened. This factcombined with their poor state of preservation,largely precludes positive identi fications. It issignificant to note, however, that none of thecrushed or flattened shells yielded any signs of

the radiating cameral deposits that characterizeEsopoceras sinuosum. This observation givessome credence to the possibility that the cameraldeposits may have functioned to provide strengthto the shell and thus prevent it from beingcrushed.

SYSTEMATIC AND MORPHOLOGIC DESCRIPTION

Class CEPHALOPODA Cuvier, 1798

Subclass ORTHOCERATOIDEAH. Schmidt, 1935

[nom , et correct. trans!. Teichert, 1967, p. 205, ex suborder Ortho-ceracea Kuhn, 1940, p. 18 (secte II. Schmidt, 1935, p. 59)]

Order ORTHOCERIDA H. Schmidt, 1935[nom. correct. et trans!. Sweet in Teichert et al., 1964, p. 223, exsuborder Orthoceracea Kuhn, 1940, p. 18 (recte 1-1. Schmidt, 1935,

0. 59 ) ]

Superfamily ORTHOCERATACEAEStokes, 1840

[nom. correct , et transi. Sweet, in Teichert et al., 1964 , p. 224, exfamily Orthoceratidae M'Coy, 1844 (secte Orthocerata Stokes, 1840,

p. 707)]

Family LAMELLORTHOCERATIDAETeichert, 1961

Genus ESOPOCERAS Stanley & Teichert, newType species.—Esopoceras sinuosum Stanley

& Teichert, n. sp.

Stanley & Teichert—Lamellorthoceratids from Lower Devonian of New York

5

Diagnosis.—Straight, slowly expanding, nearlycylindrical conchs with circular to slightly com-pressed cross section; apical angle about four tofive degrees; surface with annulations that cor-respond in position to the sutures. Three distinctshell layers are present, a thin, inner layer bearsfine costules on external side; slight ?ventral de-pression present in earlier camerae of some speci-mens; sutures with broad saddles and lobes.Siphuncle near central; septa strongly concave;cameral deposits consist of radiating, straight tosinuous and curved lamellae that converge towardthe siphuncle from the walls; both episeptal andhyposeptal deposits present; external edges oflamellae slightly to highly sinuous, showing bi-lateral symmetry with respect to dorsoventral andlongitudinal axes.

ESOPOCERAS SINUOSUM Stanley & Teichert, n. sp.

Plate 1, figures 1-9, 13; Plate 2, figures 1, 4-9

Zaphrentic cf. tabrilata Hall, Howell, 1942, P. 88, fig.15,/,2.

Diagnosis.—Same as for genus.

GENERAL MORPHOLOGY

Shell features.—The holotype (KUMIP 111622)is the steinkern of a straight, moderately expand-ing conch, which is 70 mm long (Pl. 1, fig. 6,13).Its cross section is nearly circular near the anteriorend, where the long and short diameters are 8 mmand 9 mm, respectively. The apical angle of theconch is estimated to be 6 or 7 degrees. Thephragmocone contains 16 camerae, but an apicalportion estimated to be 15-20 mm long is missing.The anterior end of the conch is somewhatcrushed and almost certainly represents at leastpart of the body chamber, because no septa canbe detected in it. This part is 12 mm long andflaring adorally. A paratype (KUMIP 111626)has a very slightly curved conch, but this isexceptional.

Since the siphuncle is nearly central and dueto the absence of external shell features, it isimpossible in the holotype and most other speci-mens to distinguish the ventral from the dorsalside. Somewhat arbitrarily, we are designatingas the ventral side that margin along which thecameral lamellae (discussed below) converge (seePl. 1, fig. 7,8).

The conch of the holotype shows a very slight

?dorsal flattening and a depression in the internalmold of the apical portion. This is present onthe first three preserved camerae and consists ofa flattened area, which toward the posterior de-velops into a slight depression. The depressionis absent adorally from the third camera. Theloss of this external feature appears to coincidewith a change in the cross-sectional shape fromlaterally compressed to more nearly circular.Just how the siphuncle position varies in rela-tionship to those changes cannot be ascertained.Another specimen (KUMIP 111627) of com-parable size shows a similar ?dorsal flattening.

The exterior of the holotype is weatheredand poorly preserved, and most of the originalshell wall has been removed. On parts of thesurface of the steinkern low annulations seem toparallel the sutures. In places where the conch ismore highly weathered, straight to somewhatsinuous, longitudinal lamellae appear on the out-side of the steinkern. These are discussed ingreater detail below.

The camerae have an average length of about4 mm, and the ratio between the length of thecamerae and their diameter varies from one-halfto one-third. The curvature of the septa cannotbe determined in the holotype, but in a paratype(KUMIP 111634), it can be seen that the septaare practically hemispherical (PI. 1, fig. 1,2). Thesiphuncle is narrow and central to subcentral inposition. The preservation of the holotype aswell as of all other specimens is such that featuresof the septal necks and connecting rings cannotbe observed, except in a poorly preserved speci-men (KUMIP 111632) which in polished crosssection shows the conch to be circular with asubcentral siphuncle. The siphuncle shows adistinct, internal, ring-like lining resembling aconnecting ring (Pl. 2, fig. 1). The exact natureof this feature is not discernible although it maybe a kind of endosiphuncular deposit. In onewell-preserved single camera (KUMIP 111626)that has a diameter of 8.0 mm, the diameter ofthe siphuncle is 1.0 mm.

From a study of all specimens, we concludethat three wall layers are present. These consistof an outer annulated layer, a middle longitudi-nally smooth layer, and an inner costulated layer.In specimen KUMIP 111623, two separate layersveneer the exterior surface of the sinuous lamellae.The first of these layers has straight longitudinal

6 The University of Kansas Paleontological Contributions—Paper 86

costules, which are overlain by a smooth layer.The relationships between the sinuous lamellaeand the longitudinally ornamented layer arewell preserved in a partially crushed portionof a phragmocone having three camerae (KUMIP111623) (Pl. 2, fig. 6). Approximately 10-12costules occur here in 5 mm of conch circumfer-ence. The sinuous lamellae are faintly visiblebelow the longitudinally ornamented veneer.

Cameral deposits.—In the holotype as well asmany other specimens the camerae are filled withcameral deposits in the form of radiating lamellaethat converge from the shell wall toward thesiphuncle (Pl. 1, fig. 6). The 14th chamber ofthe holotype reveals an excellent three-dimen-sional view of the approximately 50 lamellaepresent. At the ?ventral side of the shell, theradiating lamellae near the periphery of thecamerae are straight or only slightly sinuous andare oriented longitudinally. As the cameral lamel-lae approach the ?dorsal side of the chamber theybecome progressively more curved toward thatside, where they assume an orientation moretransverse to the conch (Pl. 1, fig. 6; PI. 2, fig.7). Another specimen (KUMIP 111624) alsoreveals an excellent three-dimensional view ofsimilarly arranged lamellae (Pl. 1, fig. 7-9).Characteristically, each individual lamella isdouble layered. The layers are generally paralleland, approaching the wall, are joined togetherto form a loop at the junction with the succeedingseptum (Pl. 1, fig. 3).

Although the holotype has a poorly preservedsurface, two other specimens exhibit excellentlythe sinuous lamellae on the weathered surface.One of these (KUMIP 111626) is a well-preservedsteinkern consisting of seven camerae (Pl. 1, fig.3). The exterior surface is weathered and thesurfaces of four camerae reveal the outer edgesof sinuous, twisted lamellae between the sutures.Although the original shell wall appears to havebeen removed by weathering, faint, straight longi-tudinal ribs can be observed on the posteriorportion. These riblike features appear to veneerthe lamellae. Approximately 12 ribs occur per5 mm of circumference.

On the surface of the steinkerns each lamellais approximately 0.2 mm wide and each is uni-form in thickness along its length. Some lamellaeare nearly straight or only slightly curved andtraverse the full length between the sutures. At

an area on the ?dorsal side, the lamellae arehighly curved, some to such an extent that theyappear to be recumbently folded (Pl. 1, fig. 7,8).Although at first glance the external edges of thelamellae seem to be randomly sinuous, a detailedexamination of two well-preserved specimens(KUMIP 111624 and 111626) as well as a clayimpression of specimen 111624 reveals that thelamellae are grouped in two distinct sectors, onecontaining generally straight or only slightlysinuous lamellae and another displaying stronglysinuous, often recumbently folded, lamellae whichconverge anteriorly (Pl. 1, fig. 8).

The contacts between these sectors are rathergradational, and we arbitrarily assume that theregion of highly folded converging lamellaecorresponds to the ventral side of the conch.The disposition and arrangement of the lamellaeon the weathered surface of the steinkern aswell as the bilateral symmetry produced by thelamellae on the ?ventral side of the conch arean expression of the internal geometry of thecameral deposits.

On the weathered surface of the steinkern(KUMIP 111626), the edges of most lamellaeare distinct and parallel. Some, however, occurin groups of two or three and coalesce in anadorai direction to form a single lamella (Pl. 1,fig. 9). This junction occurs approximately 0.5mm from the most adapical suture of the suc-ceeding chamber and produces an outward ap-pearance of dendritic branching toward theposterior.

Another specimen (KUMIP 111624) is in asimilar state of preservation although moreweathered (PI. 1, fig. 7-9). In some respects itillustrates the characteristic folding and con-vergence of the lamellae better than the previouslydescribed specimen KUMIP 111626. SpecimenKUMIP 111624 is a phragmocone, 25 mm long,containing eight chambers all of which showexternally sinuous lamellae. Plate 1, figure 8shows the surface of a rolled-out clay impressionof specimen (KUMIP 111624) illustrating thelamellae of the surface. In addition, this impres-sion shows that the sutures each have a broadsaddle and lobe. This undulation can also beseen in specimen KUMIP 111634 (Pl. 1, fig. 1,2),which is a single camera. Specimen KUMIP111624 has portions of the surface in the posteriorregion excavated by weathering. Here, lamellae

Stanley & Teichert—Lamellorthoceratids from Lower Devonian of New York 7

are straight or only slightly sinuous on the sur-face (Plate 1, fig. 9). These sinuous lamellae canalso be seen on weathered portions of the wallof specimen KUMIP 111634 (Pl. 1, fig. 1).

The cameral deposits are especially character-istic and are readily apparent in most of thespecimens as well as in polished cross sections.They have been previously mentioned in thedescription of the holotype but their presence inpolished transverse sections warrants furtherdescription.

Polished cross sections.—KUMIP 111632 is apolished circular cross section of a conch 7 mm indiameter. The cameral deposits are radiatinglamellae, some of which appear to coalesce tosome degree and merge with adjacent deposits(Pl. 2, fig. 1,4,5,9). Both episeptal and hyposeptaldeposits can be seen. An oblique view of a conchwith a circular diameter of 8 mm (KUMIP111626), shows similar radiating lamellae,especially toward the periphery of the conch(PI. 1, fig. 3).

KUMIP 111633 is a polished cross section ofthe phragmocone of a slightly larger specimenwith short and long diameters of 8 mm and 12.5mm. In this specimen the lamellae are fairlystraight in the ?ventral portion of the cameraebut those in the opposite, ?dorsal, portion arerecurved toward the ?dorsal side (Pl. 2, fig. 7).The same orientation of the lamellae can also beseen in another cross section (KUMIP 111631) inwhich approximately 50 to 60 lamellae are present.

Under microscopic examination, individualdouble-layered lamellae can be observed to sepa-rate in the proximity of the inner shell wall andthen converge at their termination (Pl. 2, fig.5,8,9; Pl. 1, fig. 4). This condition is seen inspecimen KUMIP 111633 at 0.3 to 0.4 mm fromthe shell wall. Another cross section (KUMIP111623) is partially crushed but also appears tobe compressed, having long and short diametersof 12 and 9 mm. The exterior of this specimenappears to retain some original wall structure ashas been described above. The cameral depositsappear similar to those of the previously describedcross section (KUMIP 111633), although someof the central area is obscured.

A slightly tangential polished cross section,made from one well-preserved specimen (KUMIP111623, see Pl. 2, fig. 6), reveals the nature ofthe contact between the lamellae and the inner

wall. Although the center of this cross sectionis obscure due to replacement, much detail aroundthe periphery is preserved. Microscopic examina-tion of this specimen at low magnification inreflected light reveals considerable detail (Pl. 1,fig. 4). Some of the finer features of the lamellaeobserved in a cross section (KUMIP 111633) arethe following:

Straight to slightly sinuous lamellae radiatefrom a near central siphuncle (Pl. 2, fig. 1). Thesinuous lamellae consist of two laminae whichare nearly parallel. At some points along theirlength, however, the double lamellae are in con-tact. The lamellae join together toward theperiphery of the conch near the shell wall toproduce a "double loop" appearance (PI. 1, fig.4). This can also be observed in some of thespecimens with well-preserved interiors (KUMIP111622, 111626, 111628). Specimen 111626 isillustrated in Plate 1, figure 3.

Another polished cross section, KUMIP111630, well illustrates the presence of episeptalas well as hyposeptal deposits (Pl. 2, fig. 5,9).Due to the fact that the areas between the lamellaeare replaced with clear, transparent calcite, thelamellae can be seen in threee-dimensional viewto be wavy and sinuous. Near the intersectionwith a septum in a two-dimensional plane, suchas in the plane of the thin section, they mayappear to be straight. The thickness of a pair oflooped lamellae is highly variable, ranging be-tween 0.1 mm and 0.5 mm while individuallamellae of a pair in a loop range in width be-tween 0.05 and 0.3 mm. Most paired lamellaemaking up a single cameral deposit arc approxi-mately 0.1 mm wide (Pl. 2, fig. 9).

One portion of the sectioned conch of speci-men 111623 is irregularly weathered around theperiphery and shows some inner wall structures,0.37-0.43 mm thick (Pl. 1, fig. 4). This wallstructure is largely oxidized to limonitic material,but the contact with the inner lamellae is distinct.Toward the periphery of the specimen, the in-dividual lamellae are tightly packed and bifur-cate terminally, creating a forked appearance,with the terminus of each fork extending intothe wall structure within a chamber at thecontact with the wall (Pl. 1, fig. 4). This canalso be seen in another thin section (Pl. 2, fig. 8).Some of the bifurcated terminal lamellae areslightly sinuous whereas others are straight. Most

8 The University of Kansas Paleontological Contributions—Paper 86

appear to narrow appreciably toward the wall.The length of a lamella measured from whereit bifurcates to the point at which it meets thewall is approximately 0.2 mm.

In specimens where the longitudinal, costulatewall structures are preserved (1)1. 2, fig. 6), trans-verse cross sections show that the terminal endof every other lamella occupies a position directlyadjacent to a costule and each intervening lamellaoccupies the low area of furrow between thecostules (PI. 1, fig. 4). Such a correspondenceoccurs only where the lamellae are relativelystraight. Due to the poor preservation of thematerial, details of the wall structure cannot al-ways be ascertained. In another transverse sec-tion (KUMIP 111633), the thin terminals of thebifurcated lamellae are drawn out very finely andare highly sinuous (Pl. 2, fig. 8). They eventu-ally become curved and meet the wall tangentiallyrather than terminating against it as described inKUMIP 111623. In specimen KUMIP 111623,the outer wall itself and the extending costulesappear to be filled with yellowish-orange, lami-nated, limonitic material which, in some places,is draped over the costules (Pl. 1, fig. 4). Thislimonitic material is approximately 0.05 mmthick and covers the outer surface of the speci-men. Depending on the degree of surface weather-ing, this coating overlies either the costulatedwall or the sinuous lamellae. As seen in crosssection (specimen KUMIP 111623), the individualcostules are 0.15-0.3 mm thick and, depending onthe degree of weathering, rise from 0.2 to 0.4mm above the base of the inner wall (PI. 1,fig. 4).

DISCUSSIONS AND COMPARISONS

Variations within the species.—The lamellor-thoceratids from New York are strikingly variablenot only from specimen to specimen, but alsowithin a single specimen. Variations are evidentin the shape of the conch, especially in cross sec-tion, but considerable variation is also evident inthe position of the siphuncle and in the dispositionof the radiating cameral deposits. A detailedstudy of several well-preserved phragmocones,as well as polished cross sections, has shown thatthese variations are a function of quality ofpreservation and relative position of a particularfragment within the phragmocone. Presumablysome variation is also attributable to the age of

the specimen to which the phragmocone belongs.Aside from the inherent effects of diagenetic al-teration and weathering, considerable variationsalong the length of the conch are evident. Thisis best shown in the holotype (KUMIP 111622),but unfortunately, much of the finer features ofthe exterior surface are lost due to poor preserva-tion.

The holotype is the longest and most com-plete specimen and also appears to possess aportion of the living chamber. Remarkably, inthis specimen all camerae contain cameral lamellaedeposits, which is in marked contrast to thecondition found in other orthoconic cephalopodsin which cameral deposits are weak or absent inthe youngest camerae of the phragmocone(Flower, 1955; Teichert et al., 1964; Fischer andTeichert, 1969).

Other notable variations consist of changes inthe cross-sectional shape. This is apparent inother specimens as well as the holotype in which,unfortunately, about three to four centimeters ofthe apical portion are missing. In the holotype(KUMIP 111622), the most adapical portion ofthe phragmocone is almost circular in crosssection at diameters of 6 to 8 mm. The shapeof the cross section subsequently changes afterthe first two camerae to assume a slightly com-pressed shape; this again changes to a circularshape in the last few camerae. It is difficult toassess just how much of this variation is due todeformation. Although the changes from circularto compressed are highly unusual for orthoconiccephalopods, a similar sequence seems to bepresent at approximately the same position inother specimens.

A ?dorsal depression is another possible mor-phologic variation of the conch. It occurs in thesmallest, circular portions of two specimens and,in the holotype, seems to disappear at the placewhere the change in cross-sectional shape fromcircular to compressed takes place.

The sinuosity of the outer edges of thelamellae that characterizes the exterior of theholotype, as well as of some paratypes, is dis-tinctive. Variations of the exterior excludesinuous lamellae, longitudinally striated costules,smooth, unornamented surfaces, and a surfacecharacterized by gross annulations correspondingto the sutures. These features are diagrammati-cally depicted in Figure 2. Variations in surface

Stanley & Teichert—Lamellorthoceratids from Lower Devonian of New York 9

features, in our opinion, can be attributed tovarying degrees of weathering. A careful studyof all the specimens and their surface ornamenthas shown the presence of two, or possibly three,wall layers, each possessing different characters.These are first, a longitudinally ribbed (costulate)layer (KUMIP 111634 and 111624) restingdirectly on the edges of the sinuous lamellae and,second, an overlying smooth, unornamentedlayer (111634), and possibly a third layer withan annulated surface (Pl. 1, fig. 5). This lastlayer is perceptible in the holotype but due topoor preservation, its details cannot be clearlyseen. Thus, depending on the degree of weather-ing, specimens can display any of the above sur-face ornaments.

The most intriguing characteristics of Esopo-ceras sinuosum are the internal cameral deposits,referred to as cameral lamellae. These depositsare believed to have considerable taxonomic value,but they also show great variation in symmetryand orientation. In cross section, both radial andbilateral symmetry are evident. A close study

FIG. 2. Esopoceras sintiosum Stanley 8c Teichert, n. gen.,n. sp. Diagrammatic representation of the double-layeredcameral lamellae showing differently exposed views intwo chambers. One-fourth of the cameral deposits inthe lower right chamber as well as half of those in theupper chamber are not shown; drawing is based onmorphologic features observed in several specimens andillustrates the manner in which the radiating camerallamellae become progressively curved about the longitudinalaxis of the shell. The three wall layers depicted on the

right are discussed in text.

of these cameral deposits in a variety of differenti-ally weathered and broken specimens as well aspolished cross sections has revealed considerabledetail concerning their disposition and orienta-tion. This is illustrated diagrammatically inFigure 2. Since there is much variation withincamerae, the appearance of radial versus bilateralsymmetry in cross sections appears to be depend-ent on the position of the section within a camera.In some cross sections studied, the cameral de-posits have been observed to change their orien-tation from the longitudinal to a transverse plane.This change is particularly evident in the largercamerae and occurs approximately in theirmiddle. It occurs in a progressive manner towardthe ?dorsal side where relatively straight, longi-tudinal, cameral deposits gradually assume anorientation more parallel to the septa. At thejunction with the succeeding septa, however, theychange rapidly, reverting to their former longi-tudinal, radial arrangement. Since the averagecamerae are only about 3 or 4 mm long, thischange occurs within a relatively short distance.In cross sections, within portions of the cameraewhere the cameral deposits are strongly inclinedto the transverse plane, the cameral lamellaeappear to be progressively curved toward the?ventral side (Pl. 1, fig. 6; Pl. 2, fig. 7), thusproducing bilateral symmetry. On the otherhand, where the cameral lamellae arc straightand longitudinally oriented, a distinct radiallysymmetrical pattern results (Pl. 2, fig. 1). Thus,the position of a cross section within a chamberdetermines whether it appears to be radial orbilateral in symmetry. In addition, this bilateralsymmetry becomes markedly apparent in thelarger, more proximal camerae.

The external, wavy lamellae that characterizethe exterior of many steinkerns are the outeredges of the cameral deposits. The progressivechange from relatively straight to highly twistedand folded outline (Pl. 1, fig. 7-9), correspondsto the progressive change in the orientation ofthe internal cameral deposits. In external view,the sinuous and folded external lamellae alwaysreturn to a nearly longitudinal orientation wherethey meet the next septum (Pl. 1, fig. 7-9).

Another curious feature of the cameral de-posits are the strongly curved and often con-nected structures that surround the siphuncle

(Pl. 2, fig. 4,7). Some of these are semicircular

10 The University of Kansas Paleontological Contributions—Paper 86

in cross section. They resemble circuli as illu-strated and described by Fischer and Teichert(1969). They differ from the radiating cameraldeposits primarily by having a different orienta-tion and also by being connected and thereforepresumably arising from the siphuncle rather thanthe wall.

Occurrence.—Esopus Shale (Emsian) of NewYork at a quarry near Rosendale, New York.The specimens occur in pyritized shale withbrachiopods and other orthoconic cephalopods.

Repository.—Holotype KUMIP 111622, para-types KUMIP 111623-111634, University of Kan-sas Museum of Invertebrate Paleontology, Law-rence, Kansas.

External resemblance to corals.—As previouslymentioned, the radiating, lamellar, cameral de-posits which characterize the cephalopod Arthro-phyllum in Germany, originally led Beyrich (inCarnall et al., 1850) to conclude that this fossilis a coral. A similar misidentification was latermade in North America when E. C. Stumm (inHowell, 1942) identified some fossils from theEsopus Shale of New York State as "Zaphrentiscf. tabulata Hall."

We have examined the two specimens figuredby Howell (1942) and find them to be orthoconiccephalopods and not rugose corals. They areboth almost completely replaced by marcasiteand are in such poor state of preservation as topreclude positive identification. The presenceof vague traces of sinuous external lamellae,similar to those of Esopoceras sinuosum, as wellas nearly identical dimensions of the conch sug-gest that the specimens illustrated by Howell doindeed belong to E. sinuosum. This contentionis supported further by the fact that the localityinformation for Howell's specimens indicatesthat they may have been collected from the verysame quarry that yielded the specimens wedescribe herein.

Comparisons with other lamellorthoceratidgenera.—Esopoceras bears some resemblances toother lamellorthoceratid genera. It appears to bemost similar to Lamellorthoceras (Termier andTermier, 1950), described from the Eifelian ofMorocco, with L. vermiculare as type species.In many respects Esopoceras also shows featuressimilar to two other genera, Coralloceras (Zhu-ravleva, in Ruzhentsev, 1962) and Arthrophyllum(Beyrich, in Carnall et al., 1850). The type species

of Coralloceras was first described by Le Maitre(1950) as Orthoceras coralliforme, and that ofArthrophyllum, as Orthoceras crassum Roemer(1843), later designated as type species by Roemer(1852).

Teichert (1961) restudied the original speci-mens of Lamellorthoceras vermiculare Termierand Termier (1950), compared them with Arthro-phyllum, and presented an historical account ofboth generic concepts. L. vermiculare has somefeatures in common with Esopoceras sinuosum,such as dimensions of the camerae and structureof cameral deposits. The most striking resem-blance between these two species lies in thesinuosity of the lamellae on the surface of stein-kerns and also in the interior of the camerae.Plate 1, figures 10 and 11, and Plate 2, figures2 and 3, are illustrations of external views andcross sections of L. vermiculare, four of whichwere previously figured by Teichert (1961, pl. 1,fig. 11,12; pl. 2, fig. 10,12). The strong sinuosityof the cameral lamellae in Lamellorthoceras wasalso well illustrated by Mutvei (1956, pl. 1).

Lamellorthoceras has a straight or slightlycyrtoconic conch that is circular in cross section.This genus is also characterized by sutures hav-ing broadly undulating saddles and lobes, as isalso apparent in Esopus sinuosum (PI. 1, fig.7-9). Little is known about the shell surface ofL. vermiculare, but on the surface of weatheredspecimens it can be seen that several individuallamellae converge adorally into a single lamellaas they do in Esopoceras (compare Pl. 1, fig.10,11 and Pl. 1, fig. 7-9).

Another similarity between Lamellorthocerasand Esopoceras is evident in the disposition of thecameral lamellae. Both radial and bilateral sym-metry is apparent in Lamellorthoceras just as inEsopoceras (Pl. 2, fig. 2,3). A notable degree ofsimilarity is evident in one thin section (PI. 2,fig. 3), which shows the cameral lamellae of L.vermiculare becoming progressively curved atthe ventral side near the siphuncle. We are notaware of any other genus that shows this feature.Another similarity of Esopoceras with Lamellor-thoceras can be seen in L. vermiculare at theventral side, where the lamellae converge orbend toward each other along a straight axis ofsymmetry (Pl. L fig. 10). This is comparablewith the manner in which the lamellae of someof the specimens of Esopoceras have become

Stanley &Teichert—Lamellorthoceratids from Lower Devonian of New Yok11

twisted along an axis of symmetry (Pl. 1, fig.7-9). A degree of similarity is also noted in thinsections of L. vermiculare that shows the camerallamellae becoming progressively curved towardthe ventral side, whereas in another section theypresent a more radial aspect (Pl. 2, fig. 2,3).

A major difference between Lamellorthocerasvermiculare and Esopoceras sinuosum is in theposition of the siphuncle and the shape and sizeof the conch. In Esopoceras sinuosum, thesiphuncle is central, or only slightly subcentral,whereas in Lamellorthoceras it is quite eccentric.Also, the rate of expansion of the conch of L.vermiculare appears to be much greater than thatof Esopoceras and it is much larger. As illustratedby Termier and Termier (1950) and by Teichert(1961), the siphuncle in the adapical portions ofthe conch of Lamellorthoceras lies close to theventral side and is commonly accentuated byweathering. L. vermiculare displays some rem-nants of shell ornament that consists of circularor slightly oblique striae and lirae (Termierand Termier, 1950, pl. 135, fig. 8, 9; Teichert,1961, pl. 2, fig. 1), whereas this type of ornamentis unknown in Esopoceras.

Another species, Lamellorthoceras gracile(Termier & Termier, 1950, pl. 137, fig. 5, 6)was also reillustrated by Teichert (1961, pl. 2,fig. II, 12), and this species is illustrated hereinfor comparison on Plate 1, figure 12. As describedby Termier & Termier, L. gracile differs fromL. vermiculare primarily in being more slenderand in this respect it resembles Esopoceras moreclosely. It also differs slightly in age, L. gracilebeing slightly older (Siegenian) than L. ver-miculare of Couvinian age. L. gracile has camerallamellae that are not quite as sinuous as thoseof Esopoceras sinuosum, but it resembles Eso-poceras in the bilaterally symmetrical arrange-ment of the cameral lamellae. In the New Yorkspecies, the symmetry can be shown to be de-pendent on the orientation of the lamellae withinthe chamber. This may apply to both species ofLamellorthoceras as well as to species of someother genera.

The siphuncle of Lamellorthoceras gracile ishighly eccentric (Pl. 1, fig. 12), and where itapproaches the wall, it forms a cleft or depres-sion that is enhanced by weathering. In L. gracilethis feature is much more strongly developed thanin the holotype of Esopoceras sinuosum where it

appears as a slight ?ventral depression only. Inboth Lamellorthoceras and Esopoceras the depres-sion occurs only in the most distal camerae.

The chief differences between Esopoceras andLamellorthoceras appear to be: 1) cross-sectionalshape of the conch, circular in Lamellorihoceras,but slightly compressed to circular in Esopoceras;2) details of the external edges of the lamellae,which tend to be more strongly twisted in Eso-poceras than in Lamellorthoceras; 3) dimensionsof the conch, which is much larger in Lamellor-thoceras, particularly L. vermiculare, and alsoexpands at a greater rate; 4) position of thesiphuncle, which is more eccentric in Lamella-thoceras. Shell form in Lamellorthoceras variesfrom slightly cyrtoconic to orthoconic. Only oneknown specimen (KUM1P 1 11626) of Esopocerasappears to be very slightly cyrtoconic.

Esopoceras bears some resemblance to Coral-loceras Zhuravleva (in Ruzhentsev, 1962), typespecies Orthoceras coralliforme, from the Cou-vinian of North Africa (Le Maitre, 1950). Al-though this species is comparable to Esopocerassinuosum in having sinuous external edges ofthe lamellae as well as similar chamber dimen-sions, it differs in having a greater rate of conchexpansion and in having straight, oblique sutures.Internally, Corulloceras differs markedly fromEsopoceras in having fairly straight camerallamellae which do not undulate or curve as dothose of Esopoceras. The conch of Coralloceras isdistinctly compressed dorsoventrally. Corallocerashas a characteristic ventral depression or fissurein the earliest camerae of some specimens. Theippearance of this fissure seems to be related toa change in the position of the siphuncle fromcentral to subcentral, but exact relationships arenot known.

The genus Arthrophyllum Heyrich, 1850 (typespecies Orthoceratites crassus Roemer, 1843),known from France, Germany, and Turkey, wasfirst regarded as a coral. Subsequently, Ortho-ceras kahlebergense Dahmer (1939) was assignedto Arthrophyllum (see Teichert, 1961). Thisgenus also displays slightly sinuous lamellae onthe surface of steinkerns but differs from Lamel-lorthoceras and Esopoceras in the disposition ofthe cameral deposits. Teichert (1961) noted thatArthrophyllum has simple radial cameral lamellaethat are not as undulating or twisted as those ofLamellorthoceras and Esopoceras. Furthermore,

12 The University of Kansas Paleontological Contributions—Paper 86

Teichert pointed out that in Arthrophyllum onlyepiseptal deposits appear to be present andthat these become progressively reduced in ananterior direction until they are altogether absentin the last few camerae. Such an arrangementof the cameral lamellae is not apparent inEsopoceras. One specimen of Arthrophyllumillustrated by Teichert (1961, pl. 1, fig. 7,8),shows radiating cameral lamellae that curveslightly toward the ventral side from a subcentralsiphuncle. This particular specimen shows definitebilateral symmetry in the arrangement of theedges of the lamellae and in this respect bearsmuch resemblance to Lamellorthoceras as well asEsopoceras. Schmidt (1956, p. 44) noted thatArthrophyllum has strongly folded camerallamellae. Most species of Arthrophyllum , how-ever, seem to possess straight cameral lamellae.Arthrophyllum also appears to differ fromEsopoceras in a more eccentric position of thesiphuncle, in greater rate of expansion of theconch, and in having shorter camerae.

The genus Gorgonoceras was described byZhuravleva (1961) from the Couvinian of theUrals, with G. visendum as type species. It com-pares with Esopoceras in having nearly cylindricalphragmocones with a small angle of expansionand circular cross section. It also shows distinctbilateral internal symmetry and wavy camerallamellae. Another notable similarity betweenGorgonoceras and Esopoceras is the costulateshell surface, which bears distinct longitudinalribs resembling the wall ornament in somespecimens of Esopoceras (Pl. 2, fig. 6). Speci-mens of Esopoceras have similar but somewhatfiner costules on what appears to be an innerwall layer. The arrangement of the cameral de-posits in Gorgonoceras seems to be quite differ-

ent from that of Esopoceras. Gorgonoceras con-tains cameral deposits in the form of straight,thin, radiating lamellae with one large, moremassive and distally bifid lamella occupying aventral position. Also, the chambers of Gorgon-oceras are slightly longer than those of the NewYork species.

Bahia (1964) has evaluated the genera Arthro-phyllum , Lam ellorthoceras , Coralloceras, andGorgon oceras and presented reasons for consider-ing at least three of these, Arthrophyllum, Lamel-lorthoceras , and Coralloceras, to be congeneric.He reviewed the various internal and externalfeatures used to distinguish these genera andpointed out that many of their features arcshared by all of them. This appears to beespecially true for Arthrophyllum and Lamellor-thoceras, which share many characteristics aspreviously discussed by Teichert (1961). How-ever, on the basis of differences in cameral de-posits, we are inclined to regard these as separategenera, although we concede that reasons couldbe cited for regarding all of them as subgeneraof Arthrophyllum.

The characteristics of all five genera arecompiled in Table 1 from which it can be seenthat many features and characteristics are indeedshared by different genera, and some features ofEsopoceras are shared by the previously knowngenera. It is also apparent from the foregoingdiscussions, as well as from the data presentedin Table 1, that considerable variations arepresent in all five genera. This is especially truefor the position of the siphuncle, sutures, length/width ratios of camerae, and apical angles, butprobably also for the internal arrangement anddisposition of the cameral lamellae.

SUMMARY

We consider the disposition and arrangementof the cameral deposits to be of paramount im-portance in differentiation at the specific as wellas the generic level. We have demonstrated thatin many specimens of Esopoceras cameral de-posits show intricate and complex arrangements,which are difficult to ascertain without carefulthin section study. Furthermore, it has been

pointed out that in Esopoceras there is consider-able variation not only within the camerae butalso in other characteristics such as the shape ofthe conch, length/width ratio of camerae, andthe external expression of the lamellae. Suchvariations pose considerable difficulties in taxo-nomic evaluations at the generic and specificlevels.

Stanley & Teichert-Lamellorthoceratids from Lower Devonian of New York 13

In cross sections, the cameral lamellae ofEsopoceras appear either straight or highly sinu-ous and curved, depending on the position of thesection within a camera (Pl. 1, fig. 3; Pl. 2, fig.4,7). A similar arrangement is apparent inLamellorthoceras (PI. 1, fig. 8,9). Arrangementsof the cameral lamellae in the other genera ofLamellorthoceratidae are not known in the samedetail, although the variations noted in Table 1may be attributable to internal complexities ofthe cameral deposits. We believe that, in orderto properly evaluate the taxonomic positions ofthe known genera and species, a detailed studyof the cameral deposits would be required.

The five genera of the family Lamellortho-ceratidae can be divided into two groups basedon the development of episeptal and hyposeptaldeposits and on the complexity and symmetry ofexternal lamellae, expressed on the surface ofsteinkerns. Both Arthrophyllum and Corallocerashave fairly straight cameral lamellae, which ap-pear as episeptal deposits only. Lamellorthoceras,Gorgonoceras, and Esopoceras on the other handhave both episeptal and hyposeptal deposits thatare undulatory (Table 1). Lamellorthoceras andEsopoceras have broadly undulating suture pat-terns and have external lamellae that curvearound a longitudinal axis producing pronouncedbilateral symmetry. Esopoceras differs in having

a greater degree of curvature, reflecting a cor-respondingly greater degree of internal cameralcomplexity. In Gorgon oceras, bilateral symmetryis produced in quite another way. Here, although

the cameral lamellae are wavy and undulating asin the other two genera, they are not curvedabout a longitudinal axis and are not folded ap-preciably. Instead, Gorgonoceras has a thickbifid cameral lamella in a ventral position.

Assuming the function of the cameral depositsto be hydrostatic, the arrangements in all threegenera could have achieved similar results instabilizing or balancing the conch by weightingthe shell along a ventral axis. A diagrammaticreconstruction of the arrangement of the cameradeposits in Esopoceras is presented (Fig. 2).

Considering the extreme complexity of thesedeposits, it seems that they must have beensecreted by mantle tissue in the camerae. Detailsof such a discussion are outside the scope of this

paper and the reader is referred to Flower (1955),Zhuravleva (1961), Teichert et al. (1964) and

Fischer and Teichert (1969) for a discussion of

cameral deposits and their origin. The means

by which the organism accomplished the forma-

tion of these complex systems of cameral lamellae

is a pressing problem and one on which the

lamellorthoceratids may shed more light.

REFERENCES

Babin, Claude, 1964, Presence de Lamellorthoceratidae

C. Teichert, 1961, dans l'Eifelien du Finistère: Soc.

Geol. France, Comptes Rendus Somm., fasc. 4, p.

142-144.

Camail, [Rudolf] von, Ewald, II. W.], and Roth, [LI,1850, Protokoll der Januar-Sitzung: Deutsche Geol.

Gesellsch., Zeitschr., v. 2, p. 8-10.

Dahmer, Georg, 1939, Die Cephalopoden des Oberharzer

Kahleberg-Sandsteins (Unter-Devon): Senckenbcrgiana,

v. 21, no. 5, p. 338-356.

Fenner, Peter, 1971, Defining lithostratigraphic boundaries

in homogeneous strata-A case study: Sed. Geology,

v. 6, p. 3-28.

Fischer, A. G. and Teichcrt, Curt, 1969, Cameral deposits

in cephalopod shells: Univ. Kansas Palcont. Contrib.,

Paper 37, 30 p., 4 pl.

Flower, R. H., 1955, Cameral deposits in orthoconic

nautiloids: Geol. Mag., v. 92, p. 89-103.

Howell, B. F., 1942, New localities for fossils in the

Devonian Esopus Grit of Ulster County, New York:

New York State Museum Bull. 327, p. 87-93, 1 pl.

Kuhn, Oskar, 1940, Paliiozoologie in Tabellen: 50 p., G.

Fischer (Jena).

Le Maitre, Dorothée, 1950, Orthoceratidés coralliformes

du Dévonien de l'Afrique du Nord: Soc. Geol. France,

Bull., sér. 5, v. 20, p. 93-98, pl. 8.

Mutvei, Harry, 1956, A preliminary report on the struc-

ture of the siphonal tube and on the precipitation of

lime in the shells of fossil nautiloids: Arkiv MM-

eralogi Geologi, v. 2, no. 8, p. 179-190, pl. I.

Roemer, F. A., 1843, Die Versteinerungen des Harzge-

birges: 46 p., 12 pl., Hahn'sche Hofbuchhandlung

(Hannover).

, 1852, Beitr5ge zur geologischen Kenntnis des

nordwestlichcn Harzgebirges, Zweite Abtlicilung:

Palaeontographica, v. 3, p. 67-111, pl. 11-15.

Ruzhentsev, V. E. (ed.), 1962, tvIollyuski-Geolovonogie.

I. Nautiloidei, endotseratoidei, actinotseratoidei, bak-

tritoidei, ammonoidei (agoniatity, goniatity, klimenii):

in Osnovy paleontologii, Yu. A. Orlov (ed.), 438 p.,

14 The University of Kansas Paleontological Contributions—Paper 86

99 pl., Akad. Nauk SSSR (Moskva). [Mollusks-Cepha-lopods. I. Nautiloids, endoceratoids, actinoceratoids,bactritoids, ammonoids (agoniatites, goniatites, cly-meniids), in Fundamentals of paleontology.]

Schmidt, Hermann, 1935, Einführung in die Palaeon-tologie: 253 p., 466 text-fig., Ferdinand Enke (Stutt-gart).

, 1956, Orthocone Cephalopoden aus dem deutschenUnterkarbon: Paliiont. Zeitschr., v. 30, p. 41-68, pl.2-4.

Stokes, Charles, 1840, On some species of Orthocerata:Geol. Soc. London, Trans., 2nd ser., v. 5, p. 705-714,pl. 59,60.

Teichert, Curt, 1961, Les Nautiloidcs des genres Arthro-phyllum Beyrich et Lamellorthoceras Termier etTermier: Ann. Paléontologie, v. 47, p. 93-107, 2 pl.

, 1967, Major features of cephalopod evolution: inEssays in paleontology and stratigraphy, R. C. Moorecommemorative volume, C. Teichert and E. L.Yochelson (eds.), Dept. Geology, Univ. Kansas, Spec.Pub. 2, p. 162-210, 20 text-fig., Univ. Press of Kansas(Lawrence, Kans.).

, Kummel, Bernhard, Sweet, W. C., Stenzel, H. B.,Furnish, W. M., Glenister, B. F., Erben, H. K., Moore,R. C., and Zeller, E. D. N., 1964, Treatise on Inverte-brate Paleontology, R. C. Moore (ed.), Part K,Mollusca 3. Cephalopoda-General Features, Endo-ceratoidea-Actinoceratoidea-Nautiloidca, Bactritoidea:xxviii+519 p., 361 figs., Geol. Soc. America andUniv. Kansas Press (New York and Lawrence, Kans.).

Termier, Geneviève and Termier, Henri, 1950, Invertébrésde l'ère primaire, Fasc. III, Mollusques: Vol. 2 ofPaléontologie marocaine, H. Termier (ed.), Actualitésscient, et industrielles, 1094, 246 p., 183 pl., Hermannet Cie (Paris).

, and , 1951, Sur l'éthologie du genreLamellorthoceras H. et G. Term.: Soc. Géol. France,Comptes Rendus Somm., fasc. 15 (1950), p. 277-278.

Zhuravleva, F. A., 1961, 0 redkoy forme kamernykhotlozheniy u devonskikh nautiloidey: Palcont.Zhurnal, 1961, no. 1, p. 89-94, pl. 12. [Unusual typesof cameral deposits in Devonian nautiloids.]

George D. Stanley, Jr.Department of GeologyUniversity of KansasLawrence, Kansas 66045

Curt TeichertDepartment of Geology and

Paleontological InstituteUniversity of KansasLawrence, Kansas 66045

EXPLANATION OF PLATES

PLATE 1

FIGURE

1-9. Esopoceras sinuosum Stanley & Teichert, n. sp.,Lower Devonian, New York.—/. Lateral view ofsingle camera showing twisted outer edges ofcameral lamellae, exposed through partial weather-ing of shell wall, X2. KUMIP 111634.-2. Samespecimen, septal view with near central siphuncle,X2.-3. Slightly oblique view showing sinuousouter edges of cameral lamellae; small fragment ofsucceeding septum present, X3. KUMIP 111626.—4. Photomicrograph of a polished, slightly tan-gential cross section of specimen illustrated in Pl.2, fig. 6; section is at periphery of shell and showsthe terminal, bifurcating loops of the camerallamellae as they meet the wall; darker projectionsare portions of the longitudinal costules of theinner wall, X50. KUMIP 111623.-5. Externalview of specimen with faint annulations of thesurface, X2. KUMIP 111632.-6. Transverse viewof holotype, showing slightly subcentral siphuncleand radiating lamellae which curve toward oneside, X2. KUMIP 111622.-7. Lateral viewshowing sinuous lamellae of surface of steinkern ofN.Y. sp., X2. KUMIP 111624.-8. Clay im-pression of specimen fig. 7, showing how thelamellae become progressively twisted toward acentral axis (dashed line). Some overlap present,X2.-9. Lateral view of same specimen show-ing side opposite that shown in fig. 7; posteriorregion partially weathered; note lamellae becom-ing progressively straighter from left to right.Position of sutures match with those of adjacentspecimens in figs. 7 and 9, X2.

10,11. Lamellorthoceras verrniculare Termier and Termier.—10. Ventral view, Couvinian, Morocco, X2.Specimen D8162 figured by Termier and Termier,1950, pl. 138, fig. 1, and by Teichert, 1961, pl. 2,fig. 10.-11. Dorsal view, X2. Specimen figuredby Termier and Termier, 1950, plate 135, fig. 11.

12.

Lamellorthoceras gracile Termier and Termier,ventral view, Siegenian, Morocco. Portion of

siphuncle excavated through weathering of conch,X2. Specimen Di831a figured by Termier andTermier, 1950, pl. 137, fig. 5, and by Teichert,1961, pl. 2, fig. 12.

13. Esopoceras sinuosum Stanley & Teichert, n. gen.,n. sp. Holotype, consisting of 16 camerae, X2.KUMIP 111622.

PLATE 2

FIGURE

1,4-9. Esopoceras sinuosum Stanley & Teichert, n. gen.,n. sp., Lower Devonian, New York.—/. Crosssection through a camera showing near centralsiphuncle and radially symmetrical lamellae, X4.5.—4. Same specimen as Fig. 1, ground slightlyfarther into next chamber; note curved lamellaeand bilateral symmetry, X4.5.-5. Cross sec-tion of specimen from upper left region of whichphotomicrograph figure 5 is taken, X4.5. KUMIP111630.-6. Portion of phragmocone showinglongitudinal costulcs of surface, X3.4. KUMIP111623.-7. Polished cross section showing radi-ating cameral lamellae becoming curved towardthe ?dorsal side; siphuncle not apparent, X 4.5.KUMIP 111633.-8. Photomicrograph of crosssection in which cameral lamellae meet the wall;note looped and curved nature of lamellae; speci-men mostly replaced by pyrite. KUMIP 111633.—9. Photomicrograph cross section, showing dis-tinct double-layered nature of lamellae. KUMIP111630.

2,3. Lamellorthoceras vermiculare Termier & Termier,Middle Devonian (Couvinian), North Africa.-2.Cross section; note branching lamellae and radialsymmetry, X1.9. Specimen DM 815513, figuredby Termier and Termier, 1950, pl. 135, fig. 13,and by Teichert, 1961, pl. 1, fig. 12.-3. Crosssection; note the cameral lamellae on the ?ventralside which become curved in that direction pro-ducing bilateral symmetry, X3.4. Specimen DM8155a, figured by Termier and Termier, 1950, pl.135, fig. 12, and by Teichert, 1961, pl. 1, fig. 11.

THE UNIVERSITY OF KANSAS PALEONTOLOGICAL CONTRIBUTIONS

Stanley 5- Teichert—Lower Devonian Lamellorthoceratids

Paper 86, Plate 1

8

THE UNIVERSITY OF KANSAS PALEONTOLOGICAL CONTRIBUTIONS

Paper 86, Plate 2

Stanley & Teichert—Lower Devonian Lamellorthoceratids