1)14 



NEW YORK STATE MUSEUM 



which, toward the point, die out and leave the shell smooth. 

 The figured specimen is 1% mm long and % mm in diameter 

 at the thickest part. The undulations only cover the upper 

 half of the shell. The form is about one half as large as the 

 T. gracilistriata, and does not vary materially from 

 that in shape or ornamentation. It occurs abundantly at the 

 Livonia salt shaft. Total specimens 5. 



Tentaculites bellulus Hall(?), mut. stebos Clarke 



Plate 5, fig. 8 



Orthoceras stebos Clarke. U. S. Geol. Sur. Bui. 16. 1885. p. 29 

 This is a larger and rarer form than the preceding. It is 

 characterized by its surface being covered by narrow ribs, at 

 some distance from each other, the intervals being about three 

 times as great as the width of a rib. The specimens are merely 

 fragments but show the size to be about the same as the 

 normal T. bellulus. It is found only at the Livonia salt 

 shaft, and probably represents individuals which have drifted 

 into the pyrite waters. Total specimens 2. 



CEPHALOPODA 



Genus orthoceras Breyn 

 Orthoceras subulatum Hall, mut. pygmaeum nov. 



Plate 5, fig. 6, 7 



To distinguish between O. subulatum and O. con- 

 istrictum from the cast, and without the chamber of habita- 

 tion, is impracticable; so what may represent two species is 

 placed here under one head. The shells are smooth, with a cir- 

 cular cross section, and an apical angle of 6° to 8°. The 

 siphuncle is central or nearly so. Each chamber is about one 

 third as high as its diameter. Most of the specimens are from 

 L to 2 mm in diameter, but not infrequently larger individuals, 

 up to 6 mm in diameter, occur. There is nothing other than 

 size to distinguish the pyrite forms from the normal type. The 

 appearance of these sporadic larjfe forms, as explained In the 

 introductory paragraphs, seems to be due to their having drifted 

 from noriaffedod areas' into the iron saturated waters. This 

 species occurs quite abundantly in all the localities. It is 

 usually small at Ganamdaigua hike and Livonia salt shaft. At 



