PLATE 17. 



Fig. 1. 89. 1. Ormoceras tenuifilum. (Pag. 55.) 



1. A rregment 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 annuUtions, 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 k. A loDgittidinal section passing through the siphunclc. 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 I a. 



Fig. 2. 90. 2. Ormoceras TENtriFiLirM? var. distans. (Pag. 58.) 



Fig. 3. 91. 3. Ormoceras? gracile. (Pag. 58.) 



Fig. 4. 92. 1. Endoceras sitbcentrale. ( Pag. 59.) 



