FAUNA OF THE TRIAS. 



n 



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

 acters combined which are subsequently divided among 

 different groups. There are also traces of huge s?a-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 palaeozoic; 

 and those which follow, the Trias, Oolite, and Cretaceous 

 formations, are summed tip 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 Labyrinthodonta 

 still predominate; while the Archasosauros 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 char- 

 acter 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 

 that at least a more copious preservation of organic re- 

 mains might be expected, for the oolitic strata are 

 mostly depositions which have taken place without dis- 

 turbance. 



