PLATE LXXXVI. 



Zone of Stephanoceras commune. 



Fig. 1. Stephanoceras crassum, Young 



2. 

 3. 



6. — 



7. 



10. 



Side view, natural size. Whitby. My col- 

 lection. 



— — Front view siphonal area and oral aperture. 

 Braunianum, d' ' Orbigny. View of siphonal area magnified two 



and a half diameters. My collection. 

 — — Side view of same shell, showing 



tubercles and costation magnified 

 two and a half diameters. 

 Raquinianum, — Siphonal area magnified two dia- 



meters, with suture line in situ. 

 Nailsworth. Upper Lias Sands. 

 My collection. 



— — Side view of the same fossil, showing 



the position of the tubercles and 

 lateral costse ; two diameters. 



— — Front view of the same, showing 



regular transverse costse. 

 crassum, Young. Large, well-developed specimen showing 



siphonal area, thick transverse costse, and 

 lateral tubercles in situ. Whitby. My 

 collection. 



— — Lateral view of the same fossil, showing 



the strong costse and thick whorls. 



— — Front view of the same shell, showing 



transverse costse and oral aperture. 



