1 I I PALEONTOLOGY OF NEW YORK. 



the limiting furrow distinct ; the fold gentle and the upper part of the wing 

 tlat or slightly convex; margin obliquely truncate, concave just below the 

 binge; extremit} slightly produced. 



Surface marked by fine uniform radii on the body and wing, which arc 

 nearly obsolete on the anterior end, and sometimes interrupted on the body 

 by varices of growth; also by fine concentric striae which arc acutely 

 recurved o\ r cr the angular posterior slope of the body, and crowded into 

 fascicles at irregular intervals, producing an undulated appearance. 



I nterior unknown. 



A Large left valve has a length of 52 nun., beighl lis mm., and hinge-line 

 • !ti iimi. A righl valve in the same association has a length of 4(1 mm., 

 height 20 nun., and hinge-line 33 mm. 



'This species somewhat resembles P. trigonalis, but the posterior extremity is 

 more produced, and the wing more obliquely truncate on the margin. The 

 right valve in general aspect resembles the right valve of P. alata, but the left 

 valve is very dissimilar. The distinguishing characters are its large rhomboidal 

 form, extreme gibbosity and arcuation of the left valve. 



Formation and locality. In a compact sandstone of the Upper Chemung group, 

 in the lower beds as seen at Warren, Pa. 



I'tyciioi'Teria spatulata, n. sp. 



PLATE I. XXXV. FIG. id. 



Shell large, elongate, rhomboidal; body sub-elliptical, oblique at an angle of 



about -'HI with the hinge; length more than one-third greater than the 

 height ; ante-byssal margin oblique, gently curving into the sinus, thence 

 extending into the broadly curved basal margin ; posterior end rectangularly 

 or acuteh recurved. 



Left valve moderately convex, slightly gibbous above. Right valve 

 depressed-convex, more sub-angular along the post-cardinal slope, and smaller 



than the left. 



