REPTILES 453 



Vertebrates. Shark teeth are known, but not skeletons. The 

 Dipnoan Ceratodus is very characteristic, continuing up from the 

 Permian. The Crossopterygians have greatly declined, but some 

 very large and curious fishes of this group, like Diplurus (Fig. 149), 

 still linger. The Ganoids continue to be the dominant fish-type, 



FIG. 149. — Diplurus longicaudatus. Newark shales. (Dean.) 



especially of the inland waters, and are most like the existing gar- 

 pikes. Catopterus and Ischypterus are representative American 

 genera, and Semionotus-, Dictyopyge, and Lepidotus are nearly allied 

 European fishes. 



The Amphibia reach their culminating importance in the Trias, 

 the Stegocephala multiplying and diversifying in a wonderful fash- 

 ion, and far surpassing the genera of the Carboniferous and Per- 

 mian in size. These Amphibians have been found in North 

 America, southern Africa, and Europe ; but those of the last- 

 named continent are much the best understood, because best 

 preserved, the Bunter Sandstone of Germany being a treasure- 

 house of such remains. Mastodonsaurus, Cyclotosaurus, and Laby- 

 rinthodon are common European genera, but there are many others. 

 Cheii-otherium (also European) is known only from its curious 

 footprints, like the print of a human hand. (See Fig. 85, 

 p. 230.) 



Reptilia. — It is in this class that we find the most remarkable 

 changes ; and although reptiles are common in the Permian, the 

 abundance and diversity of the Triassic reptiles are incomparably 

 greater. Almost all the orders of Mesozoic reptiles are already 

 represented in the Trias, though often by comparatively small and 



