PLATK VII. 



Platyceras undatum. 



Page 17. 

 Pigf. 1. 2. Views of the opjKieite sides of an intenial cast, showing- transverse lines of broad tubercles, and 

 grinntr the general form of the shell. The oi-iginal shell has doubtless been marked by strong- 

 spines. 



Platyceras dumosum, Conrad. 



I'nge 14. 

 V\g. 3. Dorsal view of the specimen i-epresented on Plate V, fig. 16. 



Platyceras nodostjm. 



Pago 17. 

 Figs. 4, 5. Lateral and dorsal views of an internal cast, showing vei-y strong tubercles, indicating spine-bases 

 in a somewhat quincunx an-angement. 



Platyceras crassum. 



Page 18. 

 Fig. 6. View of an internal cast which is probably of this species. Schohaiie, N. Y. 

 Fig. 7. A somewhat smaller individual which is mo^-e expanded towai-d the ajterturo, partially from com- 



l-.i-eseicm. Clarksville, Albany county, N. Y. 

 Figs. 8-10. Three views of the typical siiecinien which is a partial cast and shows great thickness of shell. 



Uelderberg muuutains, li. Y. 



