388 INFERIOR OOLITE AMMONITES. 



Sonn. dominica. (Page 410.) 

 Sonn. molticostata. (Page 410.) 



2. The outer lobule excessively exaggerated, larger than the terminal lobule. 



Fig. 15. — Outline of L of Sonn. palmata. 



Sonn. palmata. (Pages 372 and 412.) 



C. The lobes are long, but lobes or lobules may degenerate in phyletic 



development. 



a. The lobes remain long, and asymmetry is not pronounced, 

 a. Lateral lobules fairly developed. 



Flo. 16. — Outline of L of Sonn. subdecorata. Fig. 17. — Outline of L of Sonn. magnispinata. 



1. Ribs reclinate. 



* Spines small. 



Sonn. subspinosa. (Pages 358 and 412.) 

 Sonn. deoorata. 1 (Pages 360 and 412.) 

 Sonn. subdecorata. (Pages 361 and 412.) 

 Sonn. decora. (Pages 361 and 412.) 



** Spines large. 



Sonn. magnispinata. (Pages 341 and 413.) 

 Sonn. brevispinata. (Pages 343 and 414.) 



2. Bibs fairly upright. 



Sonn. mutans. (Page 414.) 



Sonn. subcostata. (Pages 330 and 415.) 



1 Suture-line unknown. 



