VIII ME GA THERIUM I 8 3 



negatived this supposition. It has shown that the Armadillos 

 are in this matter the nearest relatives of Glussotherimn. This 

 result is important as tending further to confirm the close inter- 

 relationship of all the American Edentates as contrasted with the 

 Old- World forms — a matter which has already been emphasised. 

 It is suggested, however, that the absence of under fur, which is 

 so well developed in the Sloth, and the difference shown in trans- 

 verse sections from the hair of Myrmecophaga, may be explained 

 by difference in habitat. Glossothermm lived under conditions 

 similar to those under which the Armadillos live to-day. Thus 

 the outer covering of the body became alike in the two cases, the 

 same needs supervening in both genera. 



Lcstodon is another allied genus, which seems to possess 

 canines. At any rate, in front of the four molars, and separated 

 from them by a diastema, is a smallish, somewhat canine-like 

 tooth, in both jaws. 



Megalonyx and its allies are sometimes placed in a distinct 

 family, Megalonychidae. Megalonyx itself had a skull very 

 like that of Bradijims, being shorter and not so elongated as 

 in the Mylodontidae. There is a strong tusk anteriorly, which 

 is separated by a considerable space from the three molars lying 

 behind it. Both pairs of limbs seem to have possessed five toes. 

 This is a North American genus. It differs from the bulk of 

 the American Edentates in having a complete jugal arch. 



Megatherium is the type of yet a third family, Megatheriidae, 

 of the Gravigrade Edentates. This creature is familiar from 

 the many restorations which have been built up, and from its 

 huge bulk, little short of that of an elephant. The skull, which 

 is small for the size of the creature, has a complete jugal 

 arch, from the middle of which depends a downward process as 

 in other allied forms. The teeth grow to an extraordinary 

 depth, and there are five of them in the upper and four in the 

 lower jaw — on each side of course. The fore-limbs of the 

 Megathcriii.m are very much more slender than the enormously 

 bulky hind-limbs, upon which and the equally massive tail the 

 animal seems to have supported itself while tearing down 

 branches of trees, upon whose leaves it fed. In the scapula 

 the acromion joins the coracoid as in Bradyinis ; the clavicle is 

 large. The fore-limb is four-toed, and the hind-limb three-toed. 

 The latter has but one clawed digit (the third, i.e. the inner). 



