PLATE 59. 



Page 



Fig. 1-4. Platyceras unguiforme. 322 



1 a, b, h 2. Views of young individuals of this species. 

 3 a. Profile view from the dorsal side, showing the spire and the broad flat jilications. 



3 b. Yicw of the upper side of anotlier specimen, with more numerous plications. 



4 a, var. 7nuUicarinatum. View of the lower side of a specimen which has numerous narrow 



plications. 



4 b, c. Views of the upper sides of similar specimens. 



Fig. 5 ffl - 2 & 6 c. Platyceras dilatatum. 322 



5 a, b. Young specimens of this species. 



5 c. A larger specimen, showing a shallow sinus on the back and the commencement of small 

 plications on the right side. 



5 d. A larger specimen where the plications are more fully developed. 



5 e. Dorsal view of a similar specimen in which the plications are more developed, and the 

 obtuse carina extending from the apex is more defined, and ending in a broad extension 

 in front (which is broken off' in the specimen figured ). 



5/. View of the aperture of the same specimen, showing the incipient plications ujjon the 

 left side of the aperture. ' 



5 g-. A specimen in which the spiral carina is more strongly developed, and is marked by a 

 deep sinuosity in the peristome. 



5 h. An enlargement of the surface, showing the bending of the striie as they cross the carina. 



5 i. An enlargement of the surface of a young specimen, where the longitudinal stria; are 



more conspicuous. 



6 c. This specimen is probably one of the same species, which is less expanded towards the 



aperture, and has one more volution at the apex than the preceding figures. 



Fig. 6 a, b. Platyceras tenuiliratum. 317 



6 a, b. The specimen may be a compressed form of this species. 



Fig. Q d - g, k 7 a. Platyceras oibbosum. 328 



6 d. View of the aperture of a large specimen of this species. 



6 e. A similar specimen, with less strongly plicated margins and a smaller spire. 



Qf. The upper side of the spire of fig. 6 e. The specimen is not quite symmetrical in its 

 convexity. 



6 g. The upper side of the spire of the specimen fig. 6 d. 



7 a. The lower side of a smaller specimen, showing strong plications. 



Fig. 7 b. Platyceras sulcoplicatum. 324 



7 b. The figure represents the specimen lying with the aperture downward. 



Fig. 8. * Platyceras perplicatum. 825 



8. Anterior view of the specimen. 



Fig. 9. Platyceras retrorsum. 320 



9 o, i. A specimen which is probably of this species : it is broken at the apex, and somewhat 

 otherwise distorted. 



Fig. 10. Platyceras plicatile. 325 



10 a. View of the upper side of the shell. 

 10 b. View of the aperture. 



