84 PAL/IJOSTULOC'Y OF KEW YORK. 



The specimens Jire casts of the interior preserved in coarse sandstone; the 

 surface niarlvings are consequently olditerated. 



Formation and locality. In u coarse sandstone of tlie ^'heinunu lh-oii]) near 

 Olean, Alleuhany countv, N. Y. 



Crenipecten obsoletus. 

 ri.ATK IX, ri<;s. m, -n. 



Lima* nhsdhta. Hall. Ocoloff. Siirv. N. V. : Rt'j). Fuiirtli Dist., )>. "iGS. 1843 



CnntpeeUii utmolHiin, Hall. Pal. N. Y., vul. v, i>t. 1. Plates iiml Kxplaimlimis : PI. il. lifrs. l!i, lil. 



Jan., 1S83. 



Shell .small, ohliquely sub-ovate, length nearly equal to the heiuht ; martrins 

 regularlv curved, becoming produced on the post-basal side, and somewhat 

 rectilinear on the posterior side. 



Valves very similar. Right valve depressed-convex. Left \alve regularly 

 convex. 



Hinge-line straight, a little more than one-half the length of tlu' shell. 



Beak obtuse, more proniineiit on the left valve; situated in the centre of 

 the hinge. Umbonal region well defined in the left valve; depres.sed and 

 undefined in the right valve. 



Ears small, triangular, sub-equal, delined by shallow sulci ; margins gentlv 

 concave; extremities o])tuse. Posterior ear a littl(> the larger, liyssal sinus 

 not conspicuous. 



Test thin, markeil l»y line, closely arrangeil, concentric striiv, which are 

 crowded and stronger on the ears. No radiating stria* have been discovered. 



Ligamental area narrow, marked liy a row of minute cartilagt'-pits. 



A left valve measures 18 mm. in length, 20 mm. in height, hinge-line id 

 mm. A similar right valve is 16 mm. in length, 17 mm. in height, hinge- 

 line 8.-") mm. 



Tills species bears some resemblance to C. crenulatus, but is more elongate- 

 ovate; less oblique, with the height somewhat greater than length. 



Formation and locality. In shales of the Chemung group at l'hilip,sl)urg, 

 Alleghany county, N. Y. 



