PLATE XXXVI. 



Zone of Aegoceras Henleyi. 



Fig. 1. Aegoceras heterogenic, Young and Bird* Lateral view, natural size. My 



collection. 



2. — — — Front view of the same fossil. 



3. — — Siphonal area of the same. 



4. — — Accurate tracing of the complicated 



lobe-line, showing the large 

 siphonal lobe and the larger 

 principal lateral lobes in an ex- 

 ample of this species, collected 

 from the Marlstone of the York- 

 shire coast. 



