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321

VISIT TO THE BRITISH MUSEUM.

SATURDAY, APRIL 10TH, 1880.

Director :-PROFESSOR RICHARD OWEN, C.B., F.R.S., &c., Hon,Member of the Geologists' Association.

DEMONSTRATION ON THE ELEPHANTINE MAMMALS,

(Report by PROF. OWEN.)

On this reception of the Association at the British Museum,Prof. Owen confined his observations to specimens in the NorthGallery, No.1, and here chiefly to the fossil remains of the Ele­phantine Mammals.

He called attention to the large proportion of the contents of thisGallery occupied by fossils of huge Mammalia, and contrasted thenumerical proportion of the Proboscidian ones with those of otherorders of Mammals. The contrast was, perhaps, more striking inrelation to their respective ranges in geographical distribution.

The giant of the Marsupial order was represented, as far asknown, by a single species (Diprotodon australis), and this waslimited to Australia. The Megatherioids and Glyptodons-giantsrespectively in the families of the Sloths and Armadillos-wereconfined to America. The species of each of these extinct families,nevertheless, had failed to attain the bulk of the majority of theelephant kind. A more remarkable character, perhaps, of the P"O­boscidia was their cosmopolitanism. Their remains have beenfonnd throughout a wide latitudinal range of both Europe andAsia; species now extinct once roamed over both South andNorth America. An elephant still exists in every latitude of theAfrican Continent j another existing species is limited to thewarmer latitudes of Asia and some contiguous islands. The tra­veller, Count Strzelecki, brought me from Australia an elephantinemolar, which he stated he had received from a native, who informedhim that it was from a cavern in that continent; but notwithstand­ing the number of fossil remains which have reached me fromcaves and drift deposits in nnmerous localities of Australasia, Ihave not yet got confirmatory evidence of the Australian Probo­scidiau.

322 VISIT TO THE nnrrrsa MUSEU}I.

Prof. Owen then proceeded to point out the characters ofdifferent kinds of elephantine quadrupeds. In the cabinet appro­priated to the fossil evidences of such from British localities, threespecies, at least, had roamed, most probably at different epochs,over the land now forming our sea girt country. Almost everycounty of England has contributed its evidences of these hugetenants of its original wild forest tracts.

The least incomplete evidence of an individual mammoth in theBritish Museum was the skull and tusks, obtained from fresh­water deposits, forming brick earth, in the Thames Valley, atliford, Essex. It is probable that the entire skeleton was there,for before notice of it reached the British Museum the workmenhad broken the bones they came upon week after week and carriedthem off in bags-full to sell at an "old bone shop." When theycame upon the tusks the overseer interfered, and sent notice of the" find" to the British Museum, whereupon the proper steps weretaken to secure the specimen. Ivory, after ages of deposit inmoist earth, loses its gelatine, and crumbles away at almost atouch. Before any part of this specimen was disturbed it wasthoroughly drenched by a solution of glue in hot water. Thequantity used was enormous. One of thc tusks of this skull wasestimated to have absorbed three gallons of the solution, Toughnessand tenacity being thus restored, the parts were carefully ex­humed, and form the conspicuous specimen to which the attentionof the Association was invited. By its side are photographs ofthe entire skeleton of the mammoth lately restored and articulatedfrom a similar Post-Pliocene deposit in Belgium. Besides themammoth (El. pl'imigeniu8), other kinds-e.g., El. antiquus, Fal­coner j El, priscus, Goldfuss j and E. meridionalis, Nesti-werepointed out from British localities. From other parts of theworld such fossils exhibited more numerous and striking specificand generic departures from the typical characters of the Probe­scidian group, if the existing or more recently extinct species betaken as exemplifying them.

The most numerous and obvious examples of the range of modi­fication are afforded by the grinding teeth. The essential characterof these is their massive proportions and the presence of prominentenamelled ridges crossing the crown of the molar transversely.

These ridges may be two, or two and a half, or, at most, three,in number, as in the Miocene Dinothere; they may be three, or

R. OWEN ON THE ELEPHANTINE MMDIALS. 323

four, or four and a half in number, as in the North American Mas­todon; they may be ten in number, as in the Mastodon elephan­toides of Clift and the Elephas qanesa of Cautley. From this thecross ridges of enamel increase in number to thirty (see lastlower molar of Elephas indicus, PI. II, Fig. 1). As theridges increase in number they decrease in thickness andincrease in depth, and their coat of cement increases in thick­ness. In Dinotherium and Mastodon ohioticus the cement canonly be detected, after emergence and use of the molar crown,at the bottom of the interspace of the few and thick ridges, and atthe base of the crown. As the ridges narrow, the cement rises,as it were, and finally occupies such proportion of the intervals asto constitute in the worn grinder a third distinct constituent of thetriturating surface. The second constituent is exposed by abrasionof the outer coat of enamel which invests the body or true dentinalpart of each transverse ridge.

Notwithstanding this extreme range of diversity of grindingsurface, the molars are developed agreeably with one fundamentaltype, and the homology of each tooth is determinable and demon­strable by a symbol.

Two of the three anterior grinders first developed in Dinotheriumanswer to the so-called" milk-molars" in Man, and are signifiedby the same symbols-d3, d4 (PI. II, fig. 2). They are displacedin Dinotherium vertically by two molars, which answer to the twocalled "bicuspids" in man, symbolised as p3, p4 (ib.). Theyanswer, in fact, to the last two of the four pre-molars in the pig(PI. II, fig. 3). Behind these rises a molar with three trans­verse ridges (PI. II, fig. 2, m1). It is reckoned the firstof the "true molars," though, in truth, it is a successor rather,and essentially a backward continuation, of the first (milk or deci­duous) series of teeth: it is symbolised as ml. The next molarin backward position and succession, m2 (ib.), has but two trans­verse ridges and a basal bit of the third or " talon." Such, like­wise, is the structure of the third and last molar, m3 (ib.), inDinotherium,

When we pass to the Mastodon type, we find, again, that sixgrinders succeed each other from before backwards. In the NorthAmerican Mastodon (M. ohioticus) you may see that the first issmall (d2), with two coronal elevations, and the hinder one onlyrises as a distinct transverse ridge. The second molar, d3, has two

324 VI SIT TO TIlE BIU TIS H M USE U:M.

transverse ridges; the third, d4, has three ridges; so lik ewise hasthe fourth, mI, and the fifth, m2; but the sixth and last, espe­cially in th e lower jaw, shows four transverse ridges and a basaltalon. That the second, d3, and th e third, d4, of th ese molarteeth answered to the two deciduoua teeth so symbolised in D ina­therium received welcome probability, if not proof, by the discoveryin th e Mastodon lonqirostris of the Epplesheim Miocene that one ofth ese teeth had a vertical successor, thus demonstratin g the deci­duous nature of one, at least, of the three first developed molars.Its relative position to th ese indicated it as th e successor to d3(PI. II, fig. 4), and its consequent homology with p3 developed inDinoth erium, fig. 2. This structure is, however, exceptional in theelephantine series, and th e molar dentitiou consists of six t eeth oneach side of both upper and lower jaws, the nature or homology ofwhich is now accepted as correctly symbolised (as in Fig. 5, PI. II),by d2, d3, d4, mI, m2, and m3, in both upper and lower jaw s. It isnot to be supposed, however, that the array of grinders, as shownin Fig. 5, is ever seen at the same time in the elephant. Notmore than one entire molar on each side of both jaws is in useat one time ; it may be preceded by the fag end of the worn-outmolar in front, and by the beginning of the larger molar behind.

The special modificati on of this dentition is th e progressive in­crease in size, both in length and breadth, and in th e number ofthe transverse plates of enamel-coated dentine, with cement-filledinterval s, as the molar is situated further back in the series. Aseach molar successively rises, one behind the other, it displaces itspredecessor longitudinally, and itself becomes worn away beforegiving place to the next behind, until finally the work of masti­cation is performed by a huge single grinder, the last (m3, fig . 1,PI. II), on each side of both upper and lower jaws.

As a molar moves into use it presents a grinding surface ofthe three substances or "tissues "- dentine, d, enamel, e, andcement, c, fig. 1. The adaptation of this most complex of alldental structures is plain-at least, to a teleologist. The threeseveral tissues have different degrees of density. In their applica­tion to the grinding down of tough nutritious vegetable substancesth e surface of the tooth is never worn to smoothness. The cementaltr acts yield first and most, and form the hollow-transverse channels ;the dentinal tracts have yielded in a minor degree; the enamelridges pr oject to the final wearing out of the grinder.

R. OWE:s' ON THE ELEPHA:s'TINE MAM1tIALB. 325

The composite constitution of the Geologists' " grit," calledfrom its use "mill-stone," is that which makes the slephant's" molars" truly" molary " or " mill-ston ey."

To be sure, the " Mill-stone Grit " aud the" tri-tissued tooth"both "pre-existed to their use j " and if the one was purposive orfore-ordained, fore-fashioned to its end, so may it be predicatedof the oth er j only th e species of animal forming the tooth couldnot be with out it . The tooth exis ts ill and for the elephant alone.The stone , like any oth er mineral , is selected and put to its useaccording to the needs and judgment of th e selector- viz., thehuman builder, sculptor, or machine-mak er.

The Professor next proceeded to notice another character ofProboscidian dentition, th e first to catch the eye-viz., the pairof huge tusks, which project from the upper jaw as a rule (P I. II,fig. 5. i).

These answer to a pair, pr obably the first or foremost of thet eeth called "incisors," from th eir crown being modified, in mostmammals, for cutting. They are kept in a fitting state for thisend, in the Order of Mammals in which tbe large cuttingincisors are most common and conspicuous, by mutual oppositionand att rit ion of the upper and lower pairs. In the Rodent ia,also, as in the P roboscidia, th e formative pulp is maintained, andth e chisel- teeth grow in th e ratio of th eir wear. If a hare orrabbit has the jaw broken by a shot and escapes, the healed bonemay put the upper and lower incisors "out of gear." In thatcase both pair s, by continuous growth, may become long, curved,projecting, and pointed tu sks, like those of th e elephant.

Th e Professor then directed th e at tention of the Ass ociation to

the specimen which he termed the most inst ructive of the entireelephantine series, the skull-viz., with th e lower jaw, of aMastodon angust idens (Ouvier) from the Miocene formation ofSansan, France. A pair of ever-growing incisors had been deve­loped from both upper and lower jaws, and the lower ones, beingentire, showed the oblique wear through friction against the uppertu sks, giving them the chisel character of the rodent incisors,

He next pointed out the rudimental pair of lower incisors in theskull of a new-born Ma stodon ohioiicus, and showed the mandibleof a full-grown male of that species in which one such rudimentwas retained, but requir ed removal of part of th e bone to exposeth e toothlet in its hidden alveolus.

326 VISIT TO THE BRITISH MUSEUM.

As a rule, a single pair of incisors, unopposed, grows to the sizeand shape of formidable weapons in the elephantine group; buthere, again, the retrospect into a zoology of times long past isessential to a cognizance of the range of variety in nature. Inthe extinct Dinothere the upper tusks abort and the lower pair isdeveloped (PI. II, fig. 2, i); in elephants proper the lower tusksabort and the upper pair developes. The latter is the incisorialcharacter of the two sole existing species of this once numerousand widely distributed group of gigantic mammals.

The African elephant is systematically hunted, harried, andslain for the sake of its tusks. Those of the Indian elephant areequally coveted, but the accessory value of the animal, from itsdocility as well as power, is now exclusively availed of in theAsiatic localities. The African elephants were, however, as goodservants of the Carthaginians.

The mercantile value of the tusks depends upon a peculiarmicroscopic modification of their dentine (for which reference wasmade to the" Odontography," PI. 146, fig. 8, copied in PI. II, fig. 6).True ivory may be detected by the naked eye, any transverse sectionor fracture showing minute lozenge-shaped markings due to oppositedecussating curved lines. A great proportion of ivory used by thecutlers and other trades in the North of England is or was de­rived from neither of the existing kinds of elephants, but from theextinct species which roamed over the northern latitudes of Asiaand Europe, the Elephas primiqeniue of BIumenbacb. Thenatives of such Asiatic latitudes, Tungusians and others, haveoccupied themselves for centuries in collecting the semi-fossiltusks of this species, which are bought by Russian merchants andexported for sale.

In one of such quests a Tungusian detected a pair of tusksprojecting from a vertical cliff too high for bis reach, at the mouthof the Siberian river Lena. He revisited the locality, and foundone summer that a mass of the cliff had fallen with the entire car­case of the mammoth to which the tusks belonged. Mr. Adam,an English resident at St. Petersburg, secured for that capital theskeleton and skin. The animal had a double clothing, theunder one of thick curly wool, which was covered and concealedby a coat of long blackish hair. (Some of the latter was ex­hibited.) Subsequently entire mammoths have been discoveredin an upright position in banks of the river Alassejah, in the Obi

R . OW E N ON TH E ELEPHANTINE MA~n[Ar.s. 327

peninsula. A thick coat of mud had protected th e carcase fromthe decomposing influence of the atm osphere, and subsequent. con­g elation preserved it, until recent exhumat ion. Snch well-cl adelephants would migrate, lik e their contemporaries th e musk­oxen (still existing in American polar region s), nor thward duringth e short nightless summer, as far as th e 70th degree of lati tude,where hardy shrubs push out a t emptin g but short -lived foliage.Thence the mammoths retreat ed south ward in the long winterseason.

The chief condition of th e existence of elephantine species is theextent of tree-clothed earth . The advent of man and his clearanceof forests may have been one of th e conditions of limitation of' thegeographical ranges of th e Proboscidians,

The Professor next adver ted to the origin of this peculiar formin the Mammalian Class and its affinities therein. Zoologists whomake the deciduous app endage of the fcetns a guide have placedth e elephants, some with the unguiculate carnivores, others withthe ungulate hyrac oids, t he placenta being annular or zonari al inboth these groups . Th ose who prefer the indications of cerebralst ructure deem th e eleph ants to be essentially inferior to both theungulate and , ungui culate Gyl'encephala. The brain-characterindicated by th at term is not , however, a convolutional one, butsuch relative size of th e cereb rum as makes it cover part of thecerebellum. The cerebrum may be smooth, though rela tivelylarge, as in some small monk eys, and the cerebrum may be convo­lu ted although relatively small, as in the low monotrematousE chidna. In the elephant th e cerebrum is wholly ant erior to thecerebellum. The brain-case in sections of th e skull , which werepointed out, shows the position of the cerebrum ( c, fig. 5, PI. II)to be wholly in advance of the cerebellum, b. Now, this -isessentially the brain cha racte r of th e Lissen cephala, in which : asIl. rul e, the cerebral sur face is unconvolute j and with thisgr oup of mammal s the P rofessor stated that he regarded theelephant to be affined, although its cerebrum had many convolu­tions. In the Lissencephal ous sub-class the Rodentia pres entth e most numerous marks of affinity to the Proboscidia. The cor­respondence in regard to th e ever- growing incisors had been alludedto, and the older the P roboscidian, and nearer in time to anyhypoth etical common ancestor, th e closer become th at corre­spondence, as had been pointed out ill th e specimen of th e Miocene

328 R. OWEN ON TUE ELEPHANTINE ~A~mALS.

Elephas angustidens. Reciprocally the closest correspondence, incomplexity of st ructure and relative size of the molar teeth with theelephants was to be found in th e Rodent Order. The Professoragain referred to the" Odontography" (p. 403, PI. 105, fig. 17).The structure of the grind ers in our common water-vole (Al'Vicota)recalls the structure of those in the African elephant and manyMastodons. That of th e grind ers of the Capybara (Hydrochoe7'Us,PI. II, fig. 7), has a close resemblance to that in th e Asiaticelephant. Moreover th e restricted number of premolars cha­ract erises both groups. The L eporidce, like the D inotheria, show,exceptionally, three milk-t eeth, which are push ed out by pre­molars; but the majority of Rodants develope but one premolar,as in Mastodon. Again, the presence of the five digits and theabsence of true hoofs in the elephants supplement the dentalaffinities to the Rodentia. In the Capybara, at least, the claw ofeach digit presents as near an approach to the hoof as in the footof the elephant.

But how about the character of size ? Can we venture, with thedeep-thinking Robert Ed . Grant, to call the elephant a " giganticmouse" ? This would be a fair though seemingly exaggeratedexpression of it s tru e affinities j and the Capybara, with itsgreat grinders and their many tran sverse ridges of enamel, e,dentine , d, and cement, c, is the largest among the existing R odentia.But as we grope about the dimmer regions of the past, we come uponunequivocal Rodents of greater bulk-the Trogontherium Ohioense,e.q., attained the length of six feet. Are there, it may be asked, ex­tinct Proboscidians which supplemented the Mastodontsl evidenceof " dentes scalprarii " by manifesting elephantine modifications ona diminutive scale ? Hereupon the Professor drew the attention ofthe Association to the case devoted to the interesting fossils of thedwarf elephants from the Zebbug Cave in the I sle of Malta(Elephas melitensis).

The discourse concluded with an account of the discovery byCapt. Cautly, in a sandstone quarry, of the petrified remains of hisElephas ganesa, and of the way in which the skull with the tusks,ten feet in length, had been worked out of the blocks blasted fromthe quarry, 1,000 feet above the sea level, in the Sewalik Hills,after these blocks had been received at the British Museum.