PLATE LXXXV. 



Fig. I- 



Zone of Stephanoceras commune 

 Stephanoceras subarmatum 



Young. 



3. 



4. 

 5. 



Stephanoceras fibulatum, Sower by. 



7. 



8. 

 9. 



10. 



11. — 



Side view of a variety from Whitby, 

 exhibiting the close relationship 

 existing between this species and 

 some varieties of Stephanoceras fibu- 

 latum. Natural size. My collection. 

 Side view, natural size, from Upper 

 Lias of Chipping Warden, North- 

 amptonshire, showing the spinous 

 inner whorls, and the smooth, bifur- 

 cate costse of the outer whorl. 

 Siphonal area of same shell, displaying 



its breadth and costation. 

 Suture magnified. 

 Large inornate shell, side view, showing 



the oral aperture. My collection. 

 Siphonal area and apertural expansion of 



same specimen. 

 Side view of another example, showing 

 very well the " button and loop " style 

 of costation so characteristic of the 

 species. 

 Side view of the variety termed Andrea. 

 Portion of side of a rotund variety whose 

 costse are sharp, and possess pointed 

 spines unfibulated. 

 Siphonal area of a specimen collected 

 from the Upper Lias of the Dowdes- 

 well Tunnel, showing tubercles and 

 transverse costa?. 

 Side view of a specimen from same bed 

 and locality. The fossil is identical 

 with Am. Bollenm of Quenstedt. 



