252 THE WOELD OF LIFE 



shown in Fig. 87. Yet another distinct sub-order, Pyrotheria, 

 which in its teeth somewhat resembled the extinct European 

 Dinotherium, and which had a large pair of tusks in the lower 

 jaw is found in the earlier Tertiary strata of Santa Cruz in 

 Patagonia. The elephants also had a representative among 

 these strange monsters in the form of a species of Mastodon, 

 a genus also found in North America. 



The very numerous and peculiar South American rodents 

 commonly called cavies, including the familiar gniinea-pig, are 

 well represented among these fossils, and there are many ex- 

 tinct forms. Most of these are of moderate size, but one, 

 Megamys, said to be allied to the viscachas, is far larger than 

 any living rodent, about equalling an ox in size. 



Perhaps more remarkable than any of the preceding are 

 the extinct Edei^tata which abound in all these deposits. The 

 entire order is peculiar to America, with the exception of the 

 scaly ant-eater of Asia and the aard-vark of South Africa, and 

 there is some doubt whether these last really belong to the same 

 order. The living American edentates comprise three fam- 

 ilies, generally known as sloths, ant-eaters, and armadillos, 

 each forming a well-marked group and all with a fair number 

 of distinct species. But besides these, two extinct families 

 are known, the Glyptodontidse and the Megatheriidse, the 

 former being giant armadillos, the latter equally gigantic ter- 

 restrial sloths. Both of these lived from the Miocene period 

 almost to our own time, and they are especially abundant in 

 Pliocene and Pleistocene deposits. Some of the extinct forms 

 of armadillo were very much larger than any now living; but 

 it is among the Glyptodonts, which had a continuous shield 

 over the whole body, that the largest species occurred, the shell 

 being often 6 or 8 feet long. The skeleton of one of these is 

 represented by Fig. 88. One of the most recent (Dsedicurus) 

 was 12 feet long, of which 5 feet consisted of the massive 

 armoured tail, which latter is believed to have borne a number 

 of movable horns. The earlier fossil species were of much 

 smaller size, and, though far more abundant in the south, a 



