RLATE VIII. 



Platyceeas Aroo. • 



Pil^ 19. 



Kigs. 1-3. Three views of the originally described specimen ; a partial internal cast, retaining the impres- 

 sions of' the concentric uii<lulations of the suKace. 



Ki(f. 4. View of the right 8i<^e of a specimen, partially exfoliated. Along- the middle can be traced the 

 remains of a deep notch which exi8te<i in the lip, now forming an elevated ridge somewhat 

 obscureti by adhering rock. 



Fig. !). V'iew of the opposite side of the specimen i-ejiresented in fig. 4. 



Fig. 6. Ventral view of the same, showing the depth of the shell, and the sinisti-ally coiled volutions. 



Platyceras Ammon. 



Page SO. 

 Fig. 7. View of an individual of medium size, showing the strong volutions and the peculiar laniellose 



structure. Port Colbome, Canmla. 

 Figs. 8,9. Vie W8 of the opposite sides of a large individual, showing the general form of the shell. Dai-ien, N. Y. 

 Fig. 10. Venti-al view of the sjiecimen figs. 8 and 9, showing the enrolling of the beak which in the figure is 



represented as too nearly on the same plane ; it is directed moi-e upwai-ds, leaving a gi-eater 



depth of the outer volution on the lower side. 



