156 VIEW OF THE FAUNA OF BRAZIL 



still we may assert generally, that notwithstanding the con- 

 tinuance of this group of mammals in this region from that 

 ancient period, betokens a similarity with the existing fauna, 

 as far as regards fundamental types, still there is a visible dif- 

 ference in the details of its composition, and in its subordi- 

 nate generic forms. With regard to the species of this 

 family, the greater number of them in those former ages 

 exhibited gigantic forms ; while those now existing are all 

 small animals, scarcely one reaching the middle size. We 

 may therefore conclude that this family, as now existing, 

 when compared with what it formerly was, is developed on 

 a reduced scale, as well with reference to the number of 

 genera and species, as to the size of individuals. 



Third Family, Tardigrades, Sloths. 



Two genera of this family, both now extinct, formerly in- 

 habited this district. The first of these I have spoken of in 

 my account of the Cave of Maquine, under the name of 

 Megatherium ; but subsequent investigations have satisfied 

 me that it should be separated from that genus. It has four 

 molars in the upper, and three in the lower jaw. The teeth 

 are somewhat compressed cylinders, with an even grinding 

 surface ; which, however, by trituration becomes hollowed in 

 the middle, so as to be surrounded by a continually increasing 

 margin, which, by the action of the teeth of the opposed 

 jaw, usually has some irregular indentations. These teeth 

 consist of an outer crust, composed of osseous lamin<B, partly 

 superimposed obhquely, and disposed one over the other, 

 without any immediate contact, like the plates in a Voltaic 

 pile. The teeth are fixed obliquely in the jaw ; and the last 

 molar of the upper jaw is distinguished from the rest by 

 being much smaller, and of a different shape. For this ani- 

 mal, which, in the structure of its teeth, approaches nearer 

 to the three-toed sloth than to the Megatherium^ I propose, 

 for the present, the generic name Ccelodon. I only know one 

 species, about the size of the tapir; and which, from the 

 spot where it was found, I call Ceel. Maquinense. 



The second genus of this family, which I now proceed to 

 describe, has been much longer known. It was discovered 

 and first described by President Jefferson, who took it for a 

 predatory animal ; but Cuvier was the first to determine its 

 proper place among the sloths, under the name of Megalonyx. 

 But its connection with the other animals of that order was so 

 obscure, from the imperfect state of the fragments, that Pan- 

 der and Dalton, who have described and figured the skeleton 



