916 NEW YORK STATE MUSEUM 



Bactrites (sp.) mut. parvus nov. 



Plate 5, fig. 4, 5 



Two specimens, each about 2y 2 mm in diameter, occur. The 

 surface is smooth, section circular, ventral side marked by a 

 moderately strong carina, septa slightly oblique, siphuncle un- 

 known. This suggests strongly Orthoceras marcel- 

 1 u m . Two specimens, one from Canandaigua lake, the other 

 from Livonia salt shaft. 



Genus tornoceras Hyatt 

 Tornoceras uniangulare Conrad 



Plate 5, fig. 3 



This species is the one from which the mutation to follow 

 has been derived. The specimens found in the pyrite are 

 from one fourth to one half the normal size, and appear like old 

 individuals. The species is characterized by a depressed dis- 

 coidal shell, closed umbilicus, smooth surface, thin septa, each 

 with a prominent saddle on the inner side of the disk, a deep 

 lateral lobe and a narrow, semielliptic ventral saddle. The 

 pyrite specimens, though small, are similar to the normal type. 

 They represent forms which have drifted into the pyrite- 

 depositing waters. There are 6 specimens in all, from Canan- 

 daigua lake, Livonia salt shaft and Moscow near the Delaware, 

 Lackawanna and Western Railroad. 



Tornoceras uniangulare Conrad, mut. astarte Clarke 



Plate 5, fig. 1, 2 

 Goniatites astarte Clarke. U. S. Geol. Sur. Bui. 16. 1885. p. 29 

 This form occurs with greater frequency than any other in the 

 pyrite. It appears in three distinct forms. The first is a gib- 

 bous disk, whose thickness is to the diameter as 3 is to 7. The 

 umbilicus is open and of moderate size. There are usually three 

 whorls and no indication of the dwelling chamber. The section 

 of a whorl is semielliptic, the inner side being deeply in- 

 dented by the embraced inner whorl. The inner whorl reaches 

 to about one half the night of the surrounding one. In 

 the younger whorls the indention is less. The outer shell is 

 lacking, but on the cast are light swinging striae, indicating 

 stronger striae on the outside of the shell. The septa are dis- 



