440 



THE GENERAL PRLNCIPLES OF ZOOLOGY 



the Pleistocene. Curious animals, resembling the little arma- 

 dillos of to-day, likewise lived in the American Pleistocene ; 

 the extinct genus Glyptodon is a good example (Fig. 418). It 

 attained a length of nearly three meters and was covered on 

 the dorsal surface by a greatly arched shell consisting of fused 

 bony plates in the integument ; this external skeleton was not 

 jointed, however, as in the present armadillos, and so the animal 

 could not roll itself up. 



The Ungulata have some very interesting representatives in 

 the Post-tertiary period. Here we find the woolly rhinoceros : 

 it had two horns, one anterior to the other ; its skin was with- 

 out folds and provided with a woolly covering. It lived in the 



FlU. 418. Glyptodon clavipes,-,\ lossil Edentate resembling the armadillos. (Alter Owen, 



from Parker and Haswell's Text-book.) 



north, having the same geographical distribution as the mam- 

 moth, although its first appearance on the earth was much later 

 than the first appearance of the mammoth. The reindeer had 

 a much wider distribution in the Pleistocene period than at 

 present, extending in Europe as far south as the Pyrenees. 

 The extinct Irish elk, Cervus megaceros or Megaceros hibertiicus, 

 is noteworthy because of its huge antlers, which attain an ex- 

 panse of three meters from tip to tip. The wild bull of the 

 Pleistocene, Bos primigenius, is believed to be the same as the 

 present domestic ox, Bos taunts, although much larger than 

 the latter. The Mammoth, Elephas primigenius, appears in 

 the early Pleistocene and lived until very recent times, for a 

 carved representation of it has been found. It lived in the 



