420 



SPECIAL GEOLOGY. 



Cardium truncatum, (fig. 287) and Pecten equivalvis. The 

 Brachiopoda were represented by many species of Terebra- 

 tula, and the ancient genus Spirifera, which had swarmed 



FIG. 289. 1. Spirifer Walcottii. 2. Gryphtea incurva. 3. Pleurotomaria Anglica. 

 4. Ammonites Conybeari. 



in the seas of the Silurian, Devonian, and Carboniferous 

 periods, appears in the lias for the last time. 



Sp. Walcottii is characteristic of the lower lias shales, and 



FIG. 290. Spirifera punctata. 



Sp. punctatus (fig. 290) was found in a higher bed ; the 

 genus Leptcena is represented in the lias of Ilminster. 



