346 PALEONTOLOGY OF NEW YORK. 



This species resembles P. atlenuata, but shows no constriction of the basal 

 margin, and the beaks are more nearly central. 



Formation and localities. In the shales of the Chemung group, at Philipsburgh, 

 Alleghany county, N. Y., and at Warren, Pa. 



PALiEONEILO ATTENUATA. 



PLATE L, FIGS. M-89. 



PalcBoneilo attenuata. Hall. Prelim. Notice Lamellibranchiata, 2, p. 12. 1870. 



" " " Pal. N. Y., vol. V, pt. 1. Plates and Explanations : PI. 50, figs. 34-39. 1883. 



Shell above the medium size, ovate-lanceolate in outline ; length twice the 

 height ; basal margin gently curved in the anterior and posterior portions, 

 and sinuate a little behind the middle. Posterior extremity narrowly 

 rounded. Cardinal line gently arcuate, declining posteriorly. Anterior end 

 regularly rounded. 



Valves in the posterior part, depressed-convex, with a shallow depression 

 in the middle ; the anterior portion is more convex, becoming gibbous in the 

 middle and above. 



Beaks a little in advance of the anterior third, small, little elevated above 

 the hinge. Umbonal slope rounded, scarcely defined. 



Test thin, marked by fine, closeJy-arranged striae of growth, with stronger 

 fascicles, at irregular intervals, which remain, in some degree, impressed upon 

 the cast. 



The characters of the interior are shown in figs. 35 and 36 of plate 1. 



Three specimens measure respectively 20, 31 and 42 mm. in length, and 

 10, 15 and 19 mm. in height. 



This species is readily distinguished by the elongate form, depressed-convex 

 valves, and absence of the umbonal ridge and furrow. The only species with 

 which it can be compared is P. elongata of the Chemung group. 



Formation and localities. In the Waverly sandstone, at Granville and Newark, 

 Licking county, 0. 



