PLATE 60. 



Page 



Fig. 1 & 2. Platyceeas platystomum. 326 



1 a. Vitw of tlie right side of a specimen, the apex of which is broken off. 



1 6. The cast of a similar specimen, preserving the impressions of the plications. 



2. A similar si)ccimen^ showing a little irregularity at the apex. The plications arc shown 

 onlv on one side. 



J'ig. 8. Platyceras platystomum, xar. alveatum. 32fi 



3 a. The right side, showing the upper side of the spire. 

 3 b. The left posterior side. 

 3 c. View of the aiicrture. 



Fig. 4. Platyceras retrorsum, var. abnormis. 321 



4 a. Upper side of the shell, showing the plications and the strong lamellosc striae 

 4 b. The lower side of the same, which is marked onh* by concentric lanicUose stria-. 

 4 c. An enlargement of the stria* on the upper side. 



Fig. G a - c. Platyceras' qibbosum. 



fi a, b. Two views of a much crnshed specimen of this species. 



f) c. Enlf.r^ement of the surface, showing the wrinkled transvere stria;. 



Fig. d, e. Platyceras bisulcatum. 327 



6 d. View of the ui)pcr side of the spire, showing the two sharp grooves and the limad lidies. 



6 e. The left side, showing the sinuous striae with an undefined longitudinal plication : there 

 arc, besides this, one or two obscure plications. 



