204 CARIPI. Chap. V. 



One of the principal points of distinction from other 

 families is the strong, blunt form of the claws, which 

 in one of the forms (the Capybara) are very broad, 

 and approximate in shape to the hoofs of the Pachy- 

 dermata. On this account the family is named by 

 some authors Subungulati ; the great division of mam- 

 malian animals to which the Pachydermata belong being 

 called, in the classifications of the best authors, Ungulata, 

 after the hoofed feet, which are considered their leading 

 character. It is an interesting fact that the pachyder- 

 matous animal most nearly allied to the Rodents is also 

 American, although found only in the fossil state, 

 namely, the Toxodon, which Professor Owen states 

 resembled the Eodentia in its dentition. The Toxodon, 

 on the other hand, was nearly related to the Elej)hant, 

 of which the same distinguished zoologist says, " Several 

 particulars in its organization indicate an affinity to 

 the Rodentia." These facts impart a high degree 

 of interest to these semi-hoofed American Rodents, 

 because they make it probable that these animals 

 are the living representatives, albeit somewhat modi- 

 fied, of a group which existed at a former distant 

 epoch in the world's history, and which possessed a 

 structure partaking of the characters of the two great 

 orders, Rodentia and Pachydermata, now so widely 

 distinct in the majority of their forms. I believe that 

 no remains of the order Toxodontia, or of the Rodent 

 family Subungulati, have been found fossil in any other 

 part of the world besides America. In this sort of 

 question it is very unsafe to found generalizations on 

 negative evidence ; but does not this tend to show that 



