434 



MESOZOIC ERA— AGE OF REPTILES. 





I 



NEOZOIC. 





PALAEOZOIC. 









Mesozoic. 



Cenozoic. 



Sil'n. 



Dev'n. 



Carb. 



Trias. 



Juras. 



Cret. 



Tert. 



Pres. 







Ccpha 



7 opods. 











Shelled 



or Tetra 



Dranchs. 



She 



lied. 



Nake 



d or 



i b r a i 



ichs. 



r t h < 



3 c c r a t 



i t e s . 













N 



a 



G 



u 

 oniatites. 



Na 



t 



Ceratites. 

 A ra 



ked. 



i 



m o n i 



B e 1 e ra 



1 



e s . 

 n i t e s . 



i 



d s. 















Sepia. 



Fig. 669. — Diagram showing Distribution of Cephalopods in Time. 



Crustacea. — Crustacea were rep- 

 resented in the Palaeozoic first by 

 the Trilobites ; then Eurypterids ; 

 then Limuloids ; then, in the last 

 period, by a few Macrourans. In 

 the Triassic the Macrourans be- 

 came more abundant and of more 

 modern type. In the Jurassic the 

 Macrourans continue, with also 

 many Limuloids, but the former 



Fig. 670. 



Fig. 671. 



Figs. 670, 671.— Jurassic Crustaceans: 670. 

 Eryon arctiformis, Solenhofen. 671. 

 Eryon Barrovensis, England. 



