Clarke — The Naples Fauna. 153 

 PLATE VI. 



MaNTICOCERAS CONTRACTU^!, Sp. IIOV. 



Figure 1. A } T oung shell of three volutions, x 3. This is a replacement 

 in sphalerite and retains quite perfectly the character of the 

 surface ornament. It will be observed that the primitive simple 

 varices early become duplicate or fasciculate and are especially 

 prominent on the umbilical slopes. Over the venter is a strong 

 recurvature upon the flattened hyponomic keel. 



Figure 2. An older shell, natural size ; showing the contracted umbilicus 

 and fine surface striae. 



Styliola limestone, Canandaigua lake. 



Gephxroceras cataphractum, sp. nov. 

 Figure 3. Rear view of a young shell showing the impression of a labial 

 ridge upon the surface, x 3. 



Figure 4. A young shell of three volutions, showing an almost smooth sur- 

 face, and the outline of the septum at this growth stage, x 3. 



Figures 5 and 6. Shells showing the aspect of the surface, x 3. 



Figures 7 and 9. Larger shells showing the rapid expansion of the whorl, x 3. 



Figure 8. Front view at four volutions showing the ventral course of the 

 septa and two labial ridges of the interior surface of the shell. 

 With the exception of figures 3 and 8, all specimens are barite 

 replacements. 



Java village, Wyoming county. 



Manticoceras accelerans, sp. nov. 



Figure 10. A specimen showing the very close approximation of all the 

 mhtmescens-svLturea. Natural size. 

 From the soft shales at Naples. 



Manticoceras vagans, sp. nov. 



Figures 11 and 12. Ventral and lateral views of a fragment showing the intu- 

 wiescms-suture and the sharply carinate whorl. Natural size. 

 From the upper flagstones of the Naples beds, Naples. 



