436 



MESOZOIC TIME — REPTILIAN AGE. 



St. Cassian; two species of Orthoceras have been described from the same 

 place. 



Figs. 658, 659. 



Cephalopods. — Fig. 658, Ceratites nodosus ; 658 a, dorsal view of portion of same, showing 

 the dorsal lobes of the septa ; 659, Ammonites tornatus ; 659 a, side-view of same (X %)■ 



3. Articulates. — (a.) Crustacea ns— Ostracoids : Fig. 656, Estheria (Posido- 

 m'a) minuta. — Macrourans : Fig. 660, Pemphix Sueurii, a species near the Crawfish 

 (genus Astacus). — (b.) Insects. — Species of Curcidionites, Gla- 

 phyroptera, etc. 



Fig. 660. 



4. Vertebrates. — (a.) Fishes.— Among Hybodont Sela- 

 chians, fig. 469, Hybodus plicatilis Ag. ; fig. 468, H. minor 

 Ag. Among Cestracionts, species of Acrodus, Ceratodus, 

 etc. Ganoids especially of the genera Saurichthys, Gyro- 

 lepis, Amblypterus, and Palseoniscus, the last of the hetero- 

 cercal species; and of the Pycnodont division, Pycnodus 

 gigas, etc. 



(b.) Reptiles. — (1.) Amphibians of the Labyrinthodont 

 tribe. Fig. 661, Labyrinthodon (Mastodonsaurus) giganteus, 

 reduced to one-twelfth the natural size. Fig. 661 a is one 

 of the large teeth, reduced one-half. They have the Laby- 

 rinthine structure explained on p. 280. Fig. 662 repre- 

 sents the prints of the fore and hind feet of a Chirotherium, 

 one-twelfth natural size, from a slab obtained at Hildburg- 

 hausen in Saxony, supposed to be those of a Labyrinthodon. 

 The larger track in one was eight inches long, the stride four- 

 teen inches ; in another, the length was twelve inches. Similar p^p^x g ue urii. 

 tracks have been found at Storton Hill in England. 



(2.) Lacertians and Saurians. — The species of the Trias have biconcave ver- 

 tebra?, like the Thecodonts and Enaliosaurs (in this approximating to the Fishes). 

 A species of the Permian genus Thecodontosanrus is found in the Trias at Leam- 

 ington, England. The Rhynchosaur (R. articeps Owen) had the beak of a Turtle, 

 without teeth. Simosaur, Nothosaur, Pistosaur, and Conchiosaur are names of 



