PLATE 113. 
Page 
472 
Fig. 1-5. Platyceras tortuosum. 
1-5. Views of different individuals (which are more or less perfect), showing a gradation 
in size. 
Fig. 6. Platyceras ? 473 
C. A cast; the specimen too imperfect for determination. 
Fig. 7 & 8. Platyostoma ventricosa. 469 
7. Profile of the spire of a very large specimen, which has been somewhat compressed ver¬ 
tically. 
8. View of the spire of the same specimen. The surface shows broad undulations parallel to 
the lines of growth. 
