PLATE LXXVIII. 



Zone of Stephanoceras commune. 



Fig. 1. Phtlloceras heterophyllum, Sowerby. Side view, half natural size, showing 



the fan-like dwelling-chamber. 

 2. — — — Suture line magnified. British 



Museum. 



The figured specimen was collected from the Upper Lias shales of Whitby. 



