190 



THE EDENTATES. 



Sloths are found solely in South America, 

 with the exception of a very few species 

 which extend into Central America. 



Nevertheless this simple geographical dis- 

 tribution has something unusual in it. The 

 pangolins of the East, notwithstanding their 

 armour of scales, resemble the true ant-eaters 

 of America, which are only clothed with hair, 

 but like them are entirely without teeth; the 

 earth-hogs of Africa, on the other hand, have 

 a certain though no doubt rather distant 

 resemblance in their teeth and the form of the 

 head to the armadillos. Manifestly, however, 

 these Old World forms stand in no direct 

 relation to those of South America. 



The oldest types of the edentates that we 

 know do not reach further back than the 

 Upper Miocene. In that period Greece was 

 inhabited by a giant genus, Ancylotherium, 

 France and Germany by one scarcely less 

 gigantic, Macrotherium, the latter with rather 

 long and slender limbs. The structure of 

 the teeth in the latter is somewhat similar to 

 that of the earth-hogs; and the giant of 

 Pikermi, the Ancylotherium, is also placed 

 beside this genus, which since the Miocene 

 period must have moved southwards till at 

 last it came to concentrate itself entirely in 

 Africa. 



Subsequent to the Miocene period the Old 

 World has no edentate remains to show so 

 far as is yet known. It is probable, indeed, 

 that Africa will yet yield such remains when 

 that continent has been as thoroughly explored 

 as Europe has been already. On the other 

 hand, the most curious types have been 

 brought to light from the Pliocene and 

 Quaternary strata of America. 



The Pliocene of California incloses the 

 remains of a gigantic genus, Morotherium; 

 the Quaternary caves of the eastern parts of 

 the United States contain another, Megalonyx; 

 but most types have been yielded by the 

 Pleistocene and Quaternary strata of the 

 Pampas and the caves of Brazil. The forms 

 derived from these regions are extremely 



numerous, and many of their skeletons have 

 been preserved in their smallest details. 



It is incontestable that these fossil forms, 

 now entirely extinct, fall into two groups, 

 that of the armoured Glyptodons on the one 

 hand, and that of the Megatheriums (Gravi- 

 grada] on the other hand, the latter of which 

 had a naked skin, or a skin covered only 

 with hair. The former have been ranked 

 with the armadillos, the latter with the sloths, 

 and a single genus, of which very little is 

 known, called Glossotherium, has been re- 

 garded as allied to the ant-eaters. No direct 

 ancestor of the sloths has yet been found, 

 however, and the armour-clad glyptodons 

 cannot be brought into any direct relation 

 with the armadillos, for true armadillos have 

 been found in the same strata with them. I 

 have myself had under my eyes a proof of 

 this fact, for the museum at Geneva possesses 

 the skeleton of a true fossil armadillo, which 

 unfortunately is too completely incorporated 

 with the rock in which it is embedded to be 

 capable of being entirely restored. 



Certain it is, however, that these fossil 

 types exhibit singular combinations of char- 

 acters. All of them, whether armour-clad or 

 not, show in the structure of the skull and of 

 a number of other parts of the skeleton the 

 essential characters of the sloths ; to give 

 only one instance, all of them have the typical 

 downward process from the cheek-bone. 

 Further, they are all provided with teeth, 

 which are in some cases sharply distinguished 

 from those of the sloths and armadillos. On 

 the other hand, not a single fossil genus pos- 

 sesses the slender elongated limbs of the 

 sloths; the limbs of the unarmoured, as well 

 as the armoured forms, have most resemblance 

 to those of the pichiciago. The resemblance 

 between the skeleton of the megatheriums 

 and that of the sloths is so great, that even 

 Cuvier called the megatherium, in spite of its 

 clumsy massive legs, a gigantic sloth. On 

 the other hand, the shield of the glyptodons 

 differs considerably from that of the armadillos. 



