Stephanoceras 



Lytoceras 



^goceras 



Mecho- 

 chirus 



Eryon 



Sponges 



(Cylindro- 



phyma) 



Crab 



(Palaeina- 



chus) 



Aspidoceras 



Cardioceras 



JURASSIC PERIOD 



[To face page I 



