158 



Report of the State Geologist. 



PLATE VIII. 



Gephtroceras ? (Probeloceras ?) Genundewa, sp. nov. 



Figures 1 and 2. Lateral and ventral views of a young shell, showing the 

 flattened ventral keel. From a sphalerite replacement, x 3. 



Figure 3. A somewhat larger shell in a pyritized condition ; showing the 

 course of the sutures, x 3. 



Styliola limestone, Canandaigua lake. 



Tornoceras bicostatum, Hall (sp.). 



Figures 4, 5, 6, 7 and 8. Young shells showing very wide umbilication and 

 strong, somewhat variable surface ornament. These shells are all 

 very broad on the venter, x 5. 



Figure 9. An older shell with less enlargement, showing the almost complete 

 closure of the umbilicus, x 3. 



Figures 10 and 11. An older non-umbilicate shell. Figure 11 shows the 

 breadth of the ventral keel and the deep hypnomic curves of the 

 varices, x 3. 



Figure 12. Another specimen in which umbilication is complete and low 

 ornamental lines shown, x 3. 



These specimens are all from Erie county. 



Figure 13. A small specimen from the shales at Naples, x 3. 



For illustrations of mature specimens of this species see Palaeon 

 tology of New York vol. v, pt. 2, pi. 72. 



Tornoceras rhysum, sp. nov. 



Figure 14. The only specimen observed susceptible of illustration. It shows 

 the undulate surface of the shell and the lateral course of the 

 suture, x 3. 



In association with Mantic. cataphractum at Java village, 

 Wyoming county. 



