24<3 



Report of the State Geologist. 



Genus Styliolina, Karpinsky. 



15. Styliolina fissurella, Hall. 



1879, Hall, Pal. K Y., vol 5, pt. 2, p. 178, pi. 31a. 



This little sliell is everywhere abundant in the Hamilton group. Found 

 in the lowest exposed layers, into which it passes from the underlying 

 Marcellus shale, it continues through the Hamilton beds, and into the over- 

 lying Genesee and Naples beds. One can scarcely examine the shale anywhere 

 without finding some traces of this pteropod. Some thin layers of the shale 

 seem to be completely filled with these shells, though nowhere in the 

 Hamilton group of this region is the accumulation sufficient to form bands of 

 limestone as is the case in the Genesee shale. Frequently the shells are found 

 arranged in bands or streaks along the bedding plane, as if they had been sud- 

 denly overwhelmed. The shells are all small, and usually crushed, showing 

 the line of fracture, or the " fissure " along the center. No specimens of this 

 species have been observed in the Encrinal limestone. 



Genus Coleolus, Hall. 



16. Coleolus (?) gracilis, Hall. 

 1879, Pal. X. Y., vol. 5, pt. 2, p. 190, pi. 32a. 



A specimen embedded in shale, and agreeing with the figure and descrip- 

 tion of the Chemung species was obtained from the Stroplieodonta demissa 

 bed. 



17. Coleolus tenuicinctum, Hall. 



1879, Hall, Pal. N. Y., vol. 5, pt. 2, p. 185, pi. 32, 32<t. 



This species occurs in the Nautilus bed on the lake shore. It is a rare 

 form, and has not been observed above this horizon. 



GASTEROPODA. 



Genus Platyceras, Conrad 



18. Platyceras erectum, Hall. 



1879, Hall, Pal. N. Y.. vol. 5, pt. 2, p. 5, pi. 2. 



A number of small specimens from the Stropheodonta demissa bed are 

 referred to this species. The specimens present the smooth character and 

 close coiling of this species and are probably to be regarded as immature 

 individuals. 



