96 THE NEOG^IC REALM. [CHAP. 



remarkable than any is the extinct Peltephilus of the Santa Cruz 

 deposits, in which the teeth form a continuous series up to the 

 front of the jaws, while the skull has a very broad snout, and the 

 humerus is of such a remarkable shape that it has been described 

 as that of a monotreme. Indeed this genus seems to suggest 

 that edentates are derived from animals with a fully developed 

 series of teeth in the front of the jaws. The pichiciagos (Chlamy- 

 dophorus], which are unknown before the Plistocene, form a 

 sub-family by themselves ; and yet another sub-family group is 

 indicated by the gigantic Chlamydotherium, of the Brazilian caves 

 and the Pampean, which rivalled the largest glyptodonts in size, 

 and had teeth of a more complex type than the true armadillos. 

 Other species occur in the Catamarca and Monte Hermoso Ter- 

 tiaries, although the genus is unknown in those of Patagonia. 



From the armadillos and their immediate kin the extinct 

 glyptodonts differ in having the carapace in the form of a con- 

 tinuous solid shield, without any movable bands in the middle 

 region ; in addition to which the skull is characterised by its 

 depth and shortness, while the teeth form long fluted prisms. 

 The internal skeleton, as shown in figure 19, is characterised by 

 the union of nearly the whole of the vertebrae of the back into 

 a solid girder for the support of the massive carapace ; and the 

 feet are furnished with much shorter claws than those of the 

 burrowing armadillos, the hinder ones being almost nail-like in 

 form. Most of the species from the Pampean formation are 

 animals of gigantic dimensions, the length of the carapace being 

 not unfrequently from six to eight feet ; and they are unquestion- 

 ably some of the most extraordinary creatures that ever trod the 

 earth. Although the majority are South American, some members 

 of the genus wandered as far north as Texas, while from the 

 upper division of the Loup Fork beds, corresponding to the 

 lowest Pliocene, a North American form has been described under 

 the name of Carioderma. 



In the typical genus Glyptodon, which ranges from the sand- 

 dunes and Pampean formation to the Monte Hermoso beds, the 

 tail-sheath, as shown in the annexed figure, is composed of a 

 number of spiny rings, gradually decreasing in size from the root 

 to the tip, and the polygonal plates of the carapace are each 



