THE GEOLOGICAL EECORD 213 



This earliest, but, as some think, the most extended period 

 of geological time, has been very cursorily touched upon, both 

 because its known life-forms are more fragmentary and less 

 generally familiar than those which succeeded them, and be- 

 cause the object here is to show reasons for considering it as 

 essentially 'preparatory for that wonderful and apparently sud- 

 den burst of higher life-development of which we will now en- 

 deavour to give some account. 



The Mesozoic or Secondary Formations 



When we pass from the Palaeozoic to the Mesozoic era we 

 find a wonderful change in the forms of life and are trans- 

 ported, as it were, into a new world. The archaic fishes 

 wholly disappear, while the early Amphibia (Labyrinthodonts) 

 linger on to the Trias, their place being taken by true reptiles, 

 which rapidly develop into creatures of strange forms and 

 often of huge dimensions, whose skeletons, to the uninstructed 

 eye might easily be mistaken for those of 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 Theriomorpha (or "beast-shaped'' reptiles), 

 which show some relationship to true mammals which so quickly 

 followed them in the lowest of the Mesozoic strata. 



These early reptiles already show a large amount of speciali- 

 sation. 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 discov- 

 ered in the Karoo formation of the Cape Colony, but have been 

 found in a few places in India, Europe, and Xorth America, 

 always either in the highest Primary (Permian) or lowest 

 Secondary formation (Trias). Pemains of allied forms have 

 been found in the north of England and in the Trias of Elgin, 

 Scotland. Their nearest survivimr relatives arc supposed to 



