106 ELEMENTS OF COMPARATIVE ZOOLOGY. 



layer of the skin becomes converted into bone, forming an 

 armor over the body. In the fossil Glyptodou this armor 

 formed one solid piece, enclosing the trunk much like the 

 armor of a turtle; but in the living forms it becomes 

 broken into several transverse bands, which move upon 

 each other, so that the animal can coil itself into a ball. 



The sloths are larger forms which, back downward, 

 crawl with the slowest motions along the branches of the 

 trees, holding themselves by their hook-like claws. Upon 

 the ground they walk with difficulty, their long claws 

 being in the way. In geological times there were forms 



FIG. 42. Pangolin (Mania longicaudato). From Monteiro. 



allied to the sloths, but of much larger size. One, the 

 Megatherium of South America, had a skeleton 18 feet in 

 length. Another form found in North America receives 

 interest from the fact that it was first described by Thomas 

 Jefferson. 



The ant-eaters are true edentates in that they are wholly 

 without teeth. As their name implies, ants form the chief 

 part of their food; their claws are well adapted for digging 



