FAUNA OF THE TRIAS. 73 



the Cheirotheria, or Labyrlnthodonta (colossal Batra- 

 chians) possess pre-eminently amphibian characters, and 

 exhibit, for example, several important characteristics of 

 the Batrachian skull, whereas their skin-covering recalls 

 the scale-armour of the Saurians. Thus we find cha- 

 racters combined which are subsequently divided among 

 different groups. There are also traces of huge sea-lizards. 

 But here, and likewise in the magnesian limestone for- 

 mation, these amphibian-like animals still keep in the 

 background amid the profusion of Ganoids, which espe- 

 cially characterizes some of the strata of the magnesian 

 limestone formation, the Kupferschiefer, or cupriferous 

 marl formation. For the sake of classification, the Zech- 

 stein is not unfitly supposed to conclude a great period 

 of organic development : the series of formations from 

 the Silurian to the end of the Zechstein is termed palse- 

 azoic ; and those which follow, the Trias, Oolite, and 

 Cretaceous formations, are summed up as mesozoic. 



The Trilobites, the mailed Ganoids, and others have 

 now disappeared, and the enormous development of 

 reptile life stamps this middle period. The Trias as 

 yet possesses no true Teleostei. The Labyrlnthodonta 

 still predominate; while the Archaeosauros and the Pro- 

 terosaurus, which had already appeared in the Dyas, are 

 replaced by more numerous forms approximating to the 

 true reptiles. One single discovery in the upper member 

 of the Trias — the teeth of a predatory marsupial — has 

 supplied us with the most ancient traces of a mammal. 

 It might be inferred, even from the petrographic cha- 

 racter of the oolitic strata, that this era must have been, 

 on the whole, far more favourable to the development of 

 animal life than the more perturbed Triassic period, or 



