PLATE XVI. 



Page 

 GiLBERTSocEiNus TUBERosus (Lyoii and Cass) 239 



Fig. 1. Specimen with stem. 



2. Another specimen ; ventral aspect. 



3. Ventral aspect of another specimen with additional branches in the appen- 



dages. The anal opening covered over by a Platrjceras equilaterum. 



4. Ventral aspect of another specimen. 



5. Dorsal aspect of calyx, showing the bases of the arms. 



6. A crushed specimen with appendages, arms, and pinnules. 



(All specimens in the collection of Wachsmuth and Springer.) 



