12 Calciferous of the Mohawk Valley 124 



O PHI LET A Vanuxem 



Ophileta discus, n. s., PI. 15, figs. 5, 6 



Shell discoidal, concave on the lower side; spire slightly ele- 

 vated; whorls four or more, with an elevated, sharp margin on 

 the periphery; the upper side of the whorl flat, the lower rounded 

 and somewhat angulate (see figure of lateral view, PI. 15, fig. 5). 

 Umbilicus wide, shallow, exposing all of the whorls. 



Size, 10 mm. in diameter. This species resembles Ophileta 

 ottawensis Billings, but is much smaller, the spire is slightly ele- 

 vated, and the lower side of the whorl more angulate. 



Locality. — Extremely abundant in bed No. V 2, of the Ft. 

 Hunter sedtion. 



Ophileta complanata Vanuxem, Pal. N. v., vol. i, p. 11, PI. 3. 



A number of specimens which are undoubtedly the same as 

 those referred to this species by Vanuxem and Hall were found 

 in the weathered surfaces of the rock. In every specimen the 

 surface markings were obliterated. 



PLEUROTOMARIA Defrance 



Pieurotomaria hunterensis, n. s., PI. 17, figs, i, 2, 7, S 



Shell conical; spire elevated; umbilicus more than one-half 

 as wide as the whole diameter of the shell; volutions in one speci- 

 men more than six, the upper side nearly flat with a faint groove 

 near the edge, the under side slightly angulate; aperture irregu- 

 larly rhomboidal. The size varies greatly, the largest specimen 

 included in this species being 40 mm. in diameter, the smallest 

 10 mm., the average is about 20 mm. It is possible that the 

 large specimen, PI. 17, figs. 1,2, may not be of the same species as the 

 smaller and more abundant forms, figs. 7, 8, but, until more speci- 

 mens are colle(?ted, it seems best to include them in one species. 



This species resembles P. etna Billings*, but differs from it 

 in the greater obtuseness of the apical angle, which is 65°-q5° in 

 P. etna and io8°-i20° in our species; in the umbilicus, which is 

 more than one-half the width of the shell in P. hunterensis, and 



*Geol. of Can., Pal. Fos., p. 226, fig. 210. 



