462 



MESOZOIC TIME — REPTILIAN AGE. 



from the Upper Oolite is called the Pycnodus gigas. Also Selachians, of the 

 genera Notidanus, Hybodus, Aerodus. 



(b.) Reptiles. — Fig. 739, Pterodactylus crassirostris, from Solenhofen. Fig. 

 740, section of the tooth of the Dinosaur Megalosaurus Bucklandi, Stonesfield. 

 Other Reptiles of the Oolite were the Crocodilians with biconcave vertebrse, 

 Teleosaurus (20 feet), Steneosaurus ; with convexo-concave vertebrae, Cetiosaurus 

 (60 feet), etc. ; the Lacertians, Geosaurus (12 to 13 feet long), Homseosaurus 

 (6 feet), etc.; Enaliosaurs of the genera Ichthyosaurus, Plesiosaurus, Pliosaurus. 

 Besides these, there were the earliest Chelonian remains (for only tracks of 



Figs. 739, 740. 



Fig. 739, Pterodact ylus crassirostris ( X x /i ) ; 740, Section of a tooth of Megalosaurus 



Bucklandi. 



uncertain character occur in the Triassic). The species Idiochelys Wagneri 

 (six inches long) and Eurystermim Wagleri are Turtles from Solenhofen; and 

 Chelone planiceps is from the Portland Stone. 



(c.) Birds. — None. 



(d.) Mammals. — Fig. 741, Amphitherium (Thylacotherium) Broderipii, twice- 

 natural size, Lower Oolite, Stonesfield. Fig. 742, Phascolotherium, twice natural 

 size, Stonesfield. Stereognathus is the name of another small Stonesfield species, 

 which Owen suggests may have been an herbivorous mammal. On this point 

 he says : — " Admitting the herbivority of the fossil, it is not certain that it was 

 hoofed ; there is nothing in the form and structure of the tooth to prove that. 

 Both form and structure are compatible with the hoofless muticate type of herbi- 

 vorous Mammals, as shown by the Manatee; it is the small size of the Stereo- 

 gnathus which renders it less probable that it was a diminutive kind of Manatee, 

 and more probable that it was a diminutive form of Ungulate. But, seeing the 

 manifold diversities of the multi-cuspid form of molar teeth in recent and ex- 



