62 EVOLUTION IN THE PAST 



The respiratory system, owing to lack of evidence, cannot 

 be determined. Probably the animals did not breathe in 

 infancy by means of giUs, as did the amphibians, but were 

 throughout life lung-breathers. 



Some of these Permian reptiles scarcely attained a foot 

 in length (Palcsohatteria) ; but remains of more important 

 animals quite five feet long have been found in England and 

 Germany (Proterosaurus). These various animals must have 

 looked very much like lizards, and crocodiles, in spite of 

 anatomical differences. So far as can be ascertained the 

 lizard-like Sphenodon of New Zealand has not much departed 

 from them in structure. Indeed, that now- vanishing creature 

 may almost be looked upon as an unmodified descendant of 

 the founders of all the reptile race. 

 (thero- Towards the close of the Period reptile-life became diversi- 

 MORPHS) fied by various forms with marked resemblances to mammals, 

 not only in tooth, but also in bodily structure. These advanced 

 creatures have received the name of Theromorphs, or " beast- 

 shaped." Some in possessing weU " roofed " skuUs kept 

 up a connection with the stegocephs (Pareiasaurus). These 

 heavily skuUed forms were probably of gregarious habits, and 

 spent a good deal of their time in the waters, subsisting 

 chiefly on aquatic plants. Many of them were big animals, 

 some forms attaining a length of several feet. No doubt they 

 were somewhat clumsy pedestrians when out on land- 

 excursions ; but they could when locomoting keep the 

 stomach clear of the ground. This was an achievement of 

 which a reptile might weU be proud. They appear to have 

 been prosperous animals. Their range was certainly exten- 

 sive, for remains of them are found in regions so far apart as 

 South Africa and Northern Russia. 



Their peace, it is to be feared, was occasionally disturbed 

 in some regions by certain big reptiles, likewise " beast- 

 shaped," but of a flesh-eating disposition. These thero- 

 morphs had skulls of the newer type, and their teeth were 

 decidedly more of a mammal than reptile character. Some 

 of these ferocious creatures — additional and important re- 

 mains of which have been recently discovered in Russia 

 (Professor Amalitzky, of Warsaw) — ^had tiger-like tusks 



