PLATE XXXVL 
Zone of Aegoceras Henleyi. 
Fig. 1. Aegoceras HETEROGENUM, Jb?«??^ and ^m/. 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. 
