PLATE 17. 
Fig. 1. 89. 1. ORMmocERAS 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 6. A longitudinal section passing through the sipkuncle. 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 1 a. 
Fig. 2. 90. 2. ORMocERAS TENUIFILUM? var. DISTANS. (Pag. 58.) 
Fig. 3. 91. 3. Ormoceras? GRACILE. (Pag. 58.) 
Fig. 4. 92. 1. ENDOCERAS SUBCENTRALE. ( Pag. 59.) 
