80 PALEONTOLOGY OF NEW YORK. 



quadrilineata of Sandberger, but it differs in the compound peripheral band, in 

 which feature it may be compared to P. subclatkrata of Sowerby, which is 

 somewhat similar in form, but has several cariniform revolving striae above 

 and below the peripheral band. In the comparative elevation of the spire this 

 species is intermediate between the two mentioned. It may also be compared 

 \\ itb the P. conica of Phillips, which has a tricarinate peripheral band, but no 

 carina above or below. 



Formation and localities. In shales of the Hamilton group, near Fultonham, 

 Schoharie county, the shores of Cayuga, Seneca and Canandaigua lakes, and 

 in the Genesee valley near Geneseo, N. Y. 



Plecrotomaria adjftor, n. sp. 



TLATE XXI, FIG. 16. 

 Pleurotomaria trilix, Hall. Illustrations of Devonian Fossils : Gasteropoda, pi. 20. 1876. 



Shell depressed-turbinate, obliquely ovoid-conical, wider than high. Volutions 

 convex, about four or five in the entire shell, gradually increasing in size 

 in the upper ones, and more rapidly below, the last one much expanded 

 laterally and ventricose ; lower side convex, becoming more gibbous 

 towards the aperture, and somewhat abruptly depressed into the umbilical 

 cavity. Aperture transverse, broadly oval. 



Surface marked by a simple, strong, revolving carina on the upper side of the 

 volution, a little nearer to the periphery than to the suture, and another 

 similar, but a little less strongly marked carina, at an equal distance 

 below the peripheral band, which is bicarinate, with a narrow depressed 

 space between, crossed by the slightly curving concentric striae ; strong, 

 distinct, and somewhat distant transverse striae rise from a thickened 

 band just without the suture, and extend in an almost vertical direction 

 to the carina, passing which they bend backwards somewhat abruptly to 

 the margin of the peripheral band, which is crossed by finer striae, and 

 below which the coarser striaB resume their character, and, passing the 

 lower carina, are almost as conspicuous on the lower side of the volution 



