198 THE WORLD OF LIFE CHAP. 



Mammalia, as in fact some of them have been mistaken. 

 The earliest of these new types, somewhat intermediate 

 between Amphibia and reptiles, appear in the latest of the 

 Palaeozoic strata the Permian. These are the Therio- 

 morpha (or " beast-shaped " reptiles), which show some rela- 

 tionship to true mammals which so quickly followed them in 

 the lowest of the Mesozoic strata. 



These early reptiles already show a large amount of 

 specialisation. Some have greatly developed canine teeth, 

 almost equalling those of the sabre-toothed tiger ; others were 

 adapted to feed on the luxuriant vegetation of the period, 

 while their short, massive limbs made them almost as clumsy- 

 looking as the hippopotamus. These strange creatures were 

 first discovered in the Karoo formation of the Cape Colony, 

 but have been found in a few places in India, Europe, and 

 North America, always either in the highest Primary 

 (Permian) or lowest Secondary formation (Trias). Remains 

 of allied forms have been found in the north of England and 

 in the Trias of Elgin, Scotland. Their nearest surviving 

 relatives are supposed to be the monotremes (echidna and 

 platypus) of Australia, yet in the whole series of stratified 

 rocks of Secondary and Tertiary times no intermediate form 

 has yet been discovered. 



A complete skeleton of one of the largest of these 

 beast-shaped reptiles is represented here (Fig. 45). The body 

 of this strange animal was nearly seven feet long, and its small 

 teeth show it to have been a vegetable feeder. The total 

 length of some specimens was nearly ten feet, and the immense 

 limbs were apparently adapted for digging, so that in loose 

 soil it may have been of subterranean habits. In the same 

 formation other allied but much smaller species were found. 



Along with these were many creatures of the same 

 general type, but as clearly carnivorous as the others were 

 herbivorous. About a dozen distinct genera have been 

 characterised, and as each probably comprised several 

 species, and as these have as yet been all obtained from 

 a few very limited areas, it is quite possible that the land 

 animals of the Cape Colony at that early period may have 

 been almost as numerous, as varied, and as conspicuous as 

 they are to-day. 



