160 



Report of the State Geologist. 



PLATE IX. 



Bactrites gracilior, sp. nov. 



Figures 1-7. Apical extremities with protoconch. x 25. 



Figures 1, 2, 3, 6 and 7, are barite replacements from calcareous 

 concretions at various localities in Livingston and Genesee counties. 

 Figure 1 bears a pretty sharply constricted protoconch, shows the 

 nepionic expansion and contraction of the conch and the surface 

 striation appearing directly after the embryonic period. Slight 

 differences in the size of the protoconch are noteworthy and also in 

 the depth of the constriction where it is attached to the conch (com- 

 pare fig. 6). The variation in the degree of the nepionic swelling is 

 largely due to difference in point of view. Figures 4 and 5 are from 

 specimens in pyrite, 4 exposing a part of the internal cast and 

 showing septal sutures, and 5 being an internal cast with three septa. 

 These are from soft shales at Attica, N. Y. 



Figure 8. A nearly entire shell, natural size. Griswold's, N. Y. 



Figures 9 and 10. Lateral and dorsal views of an internal cast, natural size, 

 in which the aperture is preserved entire; figure 10 shows its flaring 

 expansion and low dorsal sinus. Broad oblique undulations are 

 seen over the surface of the living chamber. Honeoye lake. 



Figures 11 and 12. Opposite sides of a barite specimen, showing the oblique 

 ridges of the surface and in fig. 12, the fine longitudinal lines. 

 Figure 11 also shows the oblique septum and fig. 12 the position of 

 the sipho. Natural size. Honeoye lake. 



Figure 13. Fragment of another specimen showing the ventral striae crossing 

 the oblique ridges. 



Figure 14. Interior of a shell showing the attachment of the siphonal por- 

 tion of the septa to the internal wall of the conch, x 3. 



Figures 15 and 16. Upper and lower sides of septa, the latter x 3. 



Bactrites aciculum, Hall (sp.). 



Figures 1 7-19. Slender embryonal tips with small protoconchs, slight nepionic 

 swellings and very gradually expanding shell. These are found in 

 association with the others, and 17 and 18 are internal casts in 

 barite. They evidently appertain to a species distinct from B. 

 gracilior, and are hence referred as above, x 25. Honeoye lake. 



