64 



ZOOLOGY OF THE VOYAGE OF THE BEAGLE. 



retained the name of Megalonyx, and used it in a generic sense, Cuvier offered no 

 characters whereby other fossil remains might be generically either distinguished 



from, or identified with the 



Jefft 



there happened to be a tooth, or a claw exactly corresponding with the descriptions 

 and figures in the Ossemens Fossiles ; and when, of course, a specific identity, and 

 not merely a generic relationship would be established. 



The greater part of Cuvier's chapter on Megalonyx is devoted to the beautiful 

 and justly celebrated reasoning on the ungueal phalanx, whereby it is proved to 

 belong, not to a gigantic Carnivore of the Lion-kind, as Jefferson supposed, but 

 to the less formidable order of Edentate quadrupeds ; and Cuvier, in reference to 

 the tooth,— the part on which alone a generic character could have been founded, 

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

 Armadillos, as it does those of the Sloths.* 



In the last edition of the Rtgne Animal, Cuvier introduces the Megatherium 



Megalony, 

 difference between the two genera than that of size, 



Megalonyx 



un peu moindre." (p. 226.) Some systematic naturalists, as Desmarest, and 



Me, 



Megatherium under the name of Megatherium Jefft 



t 



The dental charac- 



:< Dent. 



prim, et Ian. °. molares |-|, obducti, tritores, coronide nunc plana transversim sulcata 



nunc medio excavatd marginibus prominulis" 



Megalony 



Me 



rectly stated, which it is not,) is here assumed from analogy, for neither Jeffer- 



Wist 



Me 



possessed other means of knowing the dentition of that animal than were afforded 



by the fragment of a single tooth. 



Now the almost entire lower jaw about to be described offers, in so far as 

 respects the general form and structure of the teeth, the same kind and degree of 

 correspondence with the Megatherium, as does the Megalonyx Jeffersonii of 

 Cuvier : and, what is only probable in that species, is here certain, viz., an agree- 

 ment with the Me 



sively belong. The question, therefore, on which I find myself, in the outset, 

 called upon to come to a decision is, as to the preference of the mode of viewing 

 the subject of the generic relationship of the Megalonyx adopted by Desmarest, 

 Fischer, &c, or of that, on which Cuvier, and after him Dr. Harlan, have prac- 

 tically acted : whether, in short, the genus Megatherium is to rest upon the more 



* Speaking of this tooth, Cuvier observes, " Je lavois cru d'abord necessairement de paresseux ; mais aujourd- 

 hui que je connois mieux l'osteologie des divers tatous, je trouve qu'elle ressemble au moins autant a une dent de 

 Tun des grands tatous. — Loc. cit. p. 172. 



t Synopsis Mammalium. 



