PLATE 61 . 
Fig. 1. Platyceras platystoaium. 
1 a. The left posterior side of a specimen, which is crushed on the upper side. 
1 b. The anterior side of the same, the distortion being due to pressure. 
1 c. A young individual which is somewhat distorted by pressure. 
Fig. 2. Platyceras ventricosus. 
2. View of the aperture of a specimen of this species. A part of the preceding volution has 
been removed by weathering. 
Fig. 3. Platyceras pileieorme. 
8 a. The upper side of a specimen in which the apex is partially broken off. [ The minute 
volution is seen on the specimen, though not represented in the figure.] 
3 b. Profile view of a young specimen. 
Fig. 4. Platyceras perlatum. 
4 a. View looking upon the summit of the fossil. The indentation near the summit may have 
been due to the involution of the apex of the shell, which afterwards became solid, as 
the apex of the cast is not broken. 
4 b. An oblique postero-lateral view of the specimen. 
