PLATE 17. 
Fig. 1. 89. 1 . Ormoceras tenuifilum. (Pag. 55.) 
1. A fragment of this species, showing the siphon directly in contact with the ventral side of the shell, a 
portion of which remains on the lower part of the specimen. There is also a slight irregularity in the 
size of the annulations, which is a common occurrence. 
1 a. Transverse section of the last, showing the wrinkled inner surface of the siphon at the points of contrac¬ 
tion. 
1 b. A longitudinal section passing through the siphuncle. The interior is here filled with stony matter; but 
in other specimens, the inner surface of the tube presents the same wrinkled appearance along the con¬ 
tracted portions as is represented in t a. 
Fig. 2. 
90. 
2. 
Ormoceras tenotfilum? var . distans. 
(Pag. 58.) 
Fig. 3. 
91. 
3. 
Ormoceras? gracile. 
(Pag. 58.) 
Fig. 4. 
92. 
1 . 
Endoceras subcentrale. 
( Pag. 59.) 
