PLATE 60 . 
Page 
Fig. 1 & 2. Platyceras platystomum. 826 
1 a. View of tlie right side of a specimen, the apex of which is broken off. 
1 b. The cast of a similar specimen, preserving the impressions of the plications. 
2. A similar specimen , showing a little irregularity at the apex. The plications arc shown 
only on one side. 
Fig. 8. Platyceras platystomum, car . alveatum. 320 
8 a. The right side, showing the upper side of the spire. 
8 b. The left posterior side. 
3 c. View of the aperture. 
Fig. 4. 
Platyceras retrorsum, car . abnormis. 
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 only by concentric lamellose striae. 
4 c. An enlargement of the striae on the upper side. 
321 
Fig. 6 a - c . Platyceras gibbosum. 
6 a. b. Two views of a much crushed specimen of this species. 
<> c. Enlargement of the surface, showing the wrinkled transvere striae. 
Fig. 6 d, e . Platyceras bisulcatum. 827 
(i (/. View of the uppe r side of the spire, showing the two sharp grooves and the broad lobes. 
fi e. The left side, showing the sinuous striae with an undefined longitudinal plication : there 
arc, besides this, one or two obscure plications. 
