98 



reduced by the atrophy of the Uttle finger instead of the thumb. The penta- 

 dactyle species have the middle toe the largest, and some, as the Cabassou (Do- 

 sypus unicinctiis, Gm.) and the Dasypus gigas, Cuv., have two of the digits of a 

 strikingly different form from the rest : but these digits are the two inner ones, 

 or the thumb and index, which are long and slender, with simple ungual pha- 

 langes ; while the medius, annulus and minimus, or little finger, are robust, and 

 their large ungual phalanges are provided with osseous sheaths : these three digits 

 progressively and rapidly decrease in size, in the order in which they have been 

 enumerated. 



Cuvier truly observes *, that the hand of the Dasypus gigas is one of the most 

 extraordinary among quadrupeds ; but when he adds that it alone would give the 

 key to all the anomalies in that of the Megatherium, we must suppose that the 

 precise nature of these anomalies had not been rightly understood by the great 

 Palaeontologist. This at least is certain, that the three digits armed with large 

 and sheathed claws, which successively decrease in size in the hand of the Da- 

 sypus gigas, are placed on the opposite side of the hand to those digits which 

 offer the same characters in the Mylodon. In the Dasypus gigas, moreover, the 

 trapezium is a distinct bone, and supports part of the second, as well as the 

 whole of the first metacarpal bone. These metacarpal bones, which we have seen 

 to be short and thick in the Mylodon, especially the first metacarpal which is 

 as broad as it is long, are elongated, very slender, and of a simple form in the 

 Dasypus gigas. The os scaphoides is disproportionately small ; and the sole fea- 

 ture by which the organization of the hand of this existing Edental has any 

 essential correspondence with that of the Mylodon, is the articulation of the fifth 

 metacarpal, with both the cuneiform and unciform bones. In the only species 

 of Armadillo {Das. sexcinctus) in which two of the normal carpal bones are 

 blended into one, it is the trapezium and trapezoides which so coalesce, not the 

 trapezium and scaphoides. 



In the httle Chlamyphore the fifth metacarpal is unusually broad and strong, 

 and articulates with the styloid process of the ulna. The second metacarpal is 

 the longest, but the fourth and fifth are the thickest in this species ; the trape- 

 zium is distinct from both the trapezoides and the scaphoides. The ungual pha- 



* Ossemens Fossiles, loc. cit., p. 242. 



