I) 



MEGATHER1ID.E. 



MEQATHKRIIDJB. 



7U 



Urge Edentata specie* undoubtedly oorered with armour, and more 

 or lew corresponding with the characters of the Olyplodm, and 

 having established the character* of that genus on both dentary and 

 locomotive organ* ; he trusts at the same time that he hai vindicated 

 tin- ..piiu..ii of Curier with reference to the Megathere, by proving it 

 to be, by iU tegumentary covering as well aa iU osseous system, more 

 nearly allied to the Ant-Eaten and Sloths than to the Annadilloes. 

 (OeoLProc.; 1839.) 



May we venture a luggestion aa to the immediate probable cause of 

 the extinction of these and other gigantic quadrupeds whose remains 

 are found in America f The southern parts of that great continent 

 are even now subject to long-continued droughts, sometimes lasting 

 for three yeara in succession, and bringing destruction on the cattle ; 

 and, indeed, the discovery of the remains collected by Sir Woodbine 

 Parish was owing to a succession of unusually dry seasons, as we 

 hare seen. The upright position of most of these skeletons found in 

 situ, with the ponderous vertebra; and bones of the pelvis in their 

 natural situation, indicates that the animal must have' been bogged in 

 adhesive mud sufficiently firm to uphold the ponderous bones after 

 the decomposition of the soft parts. A long continued drought 

 would naturally have brought these extinct auiumla from the drained 

 and parched country to the rivers, dwindled by the continued dry 

 seasons, to a slender stream running between extensive mud banks, 

 in which these gigantic quadrupeds may have been ingulfed in their 

 anxious efforts to reach the water.* 



Megalonyx (Jefferson). Under this name Mr. Jefferson, fonnerly 

 President of the United States, described, from some bones found in 

 caverns in the west of Virginia, an extinct mammiferous animal, 

 which be considered to be carnivorous. The bones on which his 

 description was founded were, a small fragment of a femur or a 

 humerua, a complete radius, an ulna complete but broken in two, 

 three claws, t and half a dozen other bones of the foot. 



From the materials above mentioned, and on comparison with the 

 analogous bones in the Lion, Mr. Jefferson came to the conclusion 

 that the Mcyjlonyjc must have been upwards of 5 feet in height, that 

 it must have weighed nearly 900 Ibs., that it-was the largest of uugui- 

 culated iim"'', and that it was probably the enemy of the Mastodon 

 of the Ohio, as the Lion is of the Elephant When once a theory 

 takes possession of the human mind, there is generally no want ol 

 materials to confirm it in the imagination of the theorist Thui Mr 

 Jefferson appeals to certain figures resembling a Lion mentioned by 

 the most ancient historians of the Anglo-Americans as visible oil a 

 rock at the mouth of the Konhawa, a branch of the Ohio, which 

 must hare been traced by the bands of the Indians from their rude- 

 ness; and to the accounts of travellers, some of them then living 

 who had heard during the night frightful roarings which terrified the 

 dogs and the horses ; and he asks if they do not prove the existence 

 of some great unknown carnivorous species in the interior of America, 

 and whether this redoubtable animal may not hare been th 

 Mtgalonyjr I 



Dr. Wtar, Professor of Anatomy in the University of Philadelphia, 

 subsequently perceived some analogy between the bones of the fossi 

 foot of Jefferson's animal and similar bones in the foot of the Sloth 

 without other aid than Daubeuton's description. 



Cuvier, who saw at once the true analogies of the animal, and wi 

 ridiculed for his opinion by Faiijas de St. Fond, who mistook the 

 clear-sightedness of that great zoologist for the blindness of one wh 

 would constrain nature to bend to the factitious classification of an 

 artificial system, obtained costs of the bones indicated by Jefferson 

 from Mr. Peale of Philadelphia, and was afterwards furnished by SI 

 Palisot de Bcauvois, with two morceaux found in the same cavern 

 where Jefferson's specimens were discovered; fortunately one of these 

 was a tooth. With these additional materials Cuvier completed hi 

 labour*, and satisfactorily showed that the Mcyalvny.c belonged U 

 the Edentata. 



Professor Owen, in his description of his genus Mylodon, says, " Th 

 greater part of Cuvier's chapter on Mryalonys is devoted to th 

 beautiful and justly celebrated reasoning on the ungueol phalanx 

 whereby it is proved to belong not to a gigantic Carnivore of the Lioi 

 kind, as Jefferson supposed, but to the lest formidable order o 

 Kd'-ntate Quadruped* ; and Cuvier, in reference to the tooth th 

 part on which alone a generic character could have been founded 

 merely observes that it resembles at least as much the teeth of on 

 of the great Armadillors as it does those of the Sloths. In the last 

 edition of the 'Kcgne Animal ' Cuvier introduces the Mryatheriui 

 and Meijalunyx between the Sloths and Armadilloes, but alludes to n 



Mr. Darwin itaUi thtt he iru informed by an ejre-wllncM, tint during th 

 1 gran MCO ' the cattle in herd* of ihoiuand* roahcd into the Parana, ind being 

 i xhauntrd bj hunger, tbejr were unable to crawl up the muddy tnk>, and were 

 drowned, (' Voyages of the Adrenturc and Beagle between the year* 18J6 and 

 1SJ6,' TO!, ill., UI9.) Sir Woodbine ParUh ay, " la toe but great drought, 

 which continued doting the lummera of 1830, 1811, and 1832, It was calculated 

 that from a million and a half to two million! of animal* died ; the border* of 

 all the lake, and mramieU la the province were limit afterward* white with 

 their boots." ( Iluenoa Arras and the Provinces of the lUo de la Plata, 1 8ro, 



t Toe nagucal phalanx of ittfmlvnyt U much more comprcMcd than that of 



ther difference between the two genera than that of siie' j'autro, 

 a ilegalonyx, est un peu moindre.' Some systematic naturalists, aa 

 Desmarest and Fischer, have therefore suppressed the genus, and 

 made the ilegalonyx a species) of Megatherium, under the name of 



tegatherittm Jefertonii. The dental characters of the genus Megathe- 

 rium are Uid down by Fischer, as follows :' Dent prim. et. Ian. 



!i:...;.u -. 



4-4 



obducti, tritoras, coronidc uuuc plana transreraim 



ulcatA, nunc medio excaratd margiuulin prominulU.' That Mega- 

 onyx had the same number of molars as Megatherium (supposing 

 hat number in the Megathere to be correctly stated, which it is not) 

 s here assumed from analogy, for neither Jefferson, Wistar, nor 

 )uvier the authorities for Meyalonyx quoted by Fischer possessed 

 ther means of knowing the dentition of that animal than wen 

 afforded by the fragment of a single tooth." (Owen, in ' Zoology of 

 H.M.S. Beagle.' 



The same author adds, " With respect to existing Mammalia, most 

 naturalists of the present day seem to be unanimous as to the con- 

 enieuce at least of founding a generic or subgeneric distinction on 

 well-marked modifications in the form and structure of the teeth, 

 although they may correspond in number and kind,. in proof of which 

 t needs only to peruse the pages of a ' Systema Mammalium ' which 

 relate to the distribution of the Rodent order. According to thU 

 mode of viewing the logical abstractions under which species are 

 grouped together, the extinct Edentate Mammal discovered by Jefferson 

 mist be referred to a genus distinct from Megatherium, and for which 

 the term Migalonyjc should be retained. ThU will be sufficiently 

 evident by comparing the descriptions given by Cuvier of one of the 

 teeth of Megalonyj; Jeffenonii, and by Dr. Harlan of a tooth of his 

 M. larjueatu*, with those of the Megatherium which have been pub- 

 lished by Mr. Clift. The fragment of the molar tooth of the Megalvny.c 

 Jeffenonii, described and figured in the ' Ossemens Fossiles,' seems to 

 nave been implanted in the jaw like the teeth of the Megatherium by 



simple hollow base, similar in form and size to the protruded 

 crown : its structure Cuvier describes as consisting of a central cylinder 

 of bone enveloped in a sheath of enamel. The transverse section of 

 this tooth presents an irregular elliptical form, the external contour 

 being gently and uniformly convex; the internal one undulating, 

 convex in the middle, and slightly concave on each side, arising from 

 the tooth being traversed longitudinally on its inner side by two wide 

 and shallow depressions. The imperfect tooth of the species called 

 by Dr. Harlan Megalonyx laqueatui, and of which a cast was presented 

 by that able and industrious naturalist to the Museum of the Hoyal 

 College of Surgeons, resembles in general form, and especially in the 

 characteristic double longitudinal groove on the inner side, the tooth 

 of the Megalonyx Jrfferionii." 



Two claws of the fore foot, a radius, humerus, scapula, one rib, an 

 os calcis, a metacarpal bone, some vertebra, a femur, and a tibia of 

 Megalonyx laqueatui, which were discovered in Big-Bone Cave, 

 Tennessee, United States, are also described by Dr. Harlan, who, 

 though he does not enter into the question of the generic characters 

 of Megalonyx, seems, as Professor Owen observes, to feel that they do 

 not rest entirely on dental modifications; for Dr. Harlan remarks 

 that " a minute examination of the tooth and knee-joint renders it 

 not improbable, supposing the last-named character to be peculiar t<> 

 it, that if the whole frame should hereafter be discovered, it may even 

 claim a generic distinction, in which case either Aulaxotlon or fleurodon 

 would not be an inappropriate name." Upon this Professor Owen 

 makes the following pertinent observation : " There can be no doubt, 

 as it appears to me, with respect to a fossil jaw presenting teeth in the 

 same number and of the same general structure as in the Megatherium, 

 and with individual modifications of form as well marked as those 

 which distinguish Megatherium from Megalonyx, that the pahcrmto- 

 logist has no other choice than to refer it, either as Fischer has done 

 with Mcgalonyf, to a distinct species of the genus Megatherium, or to 

 regard it as a type of a sub-genus distinct from both. With reference 

 however to the Pleurodon of Dr. Harlan, after a detailed comparison 

 of the cast of the tooth on which that genus is maiuly founded with 

 the descriptions and figures of the t joth of the Mcgalonyx Jeffenonii 

 in the ' Ossemens Fossiles,' they seem to differ in so slight a degree as 

 to warrant only a specific distinction, and this difference even, viewing 

 the various proportions of the teeth in the same jaw of the Mcjutlif- 

 riitm, is more satisfactorily established by the characters pointed out 

 by Dr. Harlau, in the form and proportions of the r.Klius, than by 

 those of the tooth itself." 



Among the bones collected by Spix and Martins in the cave of 

 Lassa Grande, near the Arraval do Torracigos in Brazil, and described 

 by Professor Doellinger, t there were no teeth, and only a few bones 

 of the extremities. The Professor concludes from their shape, the 

 presence of an osseous sheath for the claw, and from the form of their 

 articulation, that they doubtless belong to a Megatheroid animal of 

 the size of an Ox. The bones, according to the Profeesor, are not 

 those of an immature Individual, and agree sufficiently with Cm i>T' 

 descriptions and figures of the Megalvnyj- to warrant their being referred 

 to that kind of animal. 



' Medical and Physical Rcsearche*,' p. 323, Ac. 

 t SpU and Martiu*, ' Kciso ia llrnzil, 1 band U., p. 4. 



