166 NEW YORK STATE MUSEUM 



7.9 mm. In the other form the sinus is shallow and the surface 

 pits elongated and faintly marked. The brachial valve corre- 

 sponds with the type. These specimens are also slightly larger, 

 measuring 7 mm by 9 mm. There are, however, intermediate 

 forms connecting these two extremes. 



In bed I the average shell measures: length 5.3 mm, width 7.2 

 mm; but in the upper limestone beds they agree in size with the 

 largest specimens in the shales. 



TREMATOSPIRA Hall 



Trematospira gibbosa Hall 



Pal. N. Y. 4:272, pi. 45 



A nearly perfect specimen was found in bed VII, and numer- 

 ous incomplete shells in bed VIII. They are partially exfoliated, 

 but show the characteristic punctate surface and crowded plica- 

 tions of the fold and sinus. 



NUCLEOSPIRA Hall 



Nucleospira concinna Hall 



Pal. N. Y. 4:279, pi. 45 



Shells of this species are rare in bed III. A few partially exfo- 

 liated specimens showing the subequally convex valves and 

 characteristic surface markings were found. Measurements: 

 length 7 mm, width 8.5 mm, convexity 3.5 mm. 



MERISTELLA Hall 



Meristella barrisi Hall 



Pal. N. Y. 4:304, pi. 69 



This is the most common fossil in beds VII and VIII. The 

 shells are large, some of them extremely gibbous, and they 

 exhibit the characteristic features of the species. Several 

 specimens have been found in bed F immediately above the 

 limestone. 



