•J4 PAL.EOyTOLOGY OF NEW YORK. 



sinus, iind Irom the sides of the uiiiho l»y a sulcus ; the byssal sinus is deep and 

 rounded. 



Test iiiarkid liv line alternatinj!; filiform radiatinj? stri*, which are absent 

 on tlic cars, except as two or three alternating undulations. Fine lines of 

 growth mark tiie test and extend over the ears. 



Liganiental area lincin- and marked ])y an inflection of the hinge-margin. 



The specimen has a height of 1". mm. and a length of 13 mm., hinge- 

 line 10 mm. About 13 rays occupy the space of 5 mm., measured near the 

 basal margin. 



This form may be distinguished Ity its equilateral proportions, acute, 

 straight apex, the non-ohli([uity of the transverse axis to the liinge-line, the 

 broad, triangular ears and the alternating surface striae. These characters sepa- 

 rate it from A. striatus, to which it is most nearly allied. 



Formation and locality. In sandstone of the conglomerate, associated with 

 till' upper Chemung grou]». at Salamanca, Cattaraugus county, N. Y. 



AviCULOPECTEN PATULUS. 



PLATE VH, KlUS. 3-', Si. 



Avicidopeeten patiilm. Ham,. P.il. N. V.. vol. v. i>t. 1. Platc.^* ami Exiilanations ; PI. P. tif.'s. 32, 33. 



Jan., 1883. 



Shell large, longitudinally broadly elliptical ; height alujut five-sixths as great 

 as the length. The axis of greatest height is at right angles to the hinge, 

 and the line of greatest length is parallel to the hinge and across the middle 

 of the shell. Basal margin convex, somewhat Hatteiied in the niiddle. 

 Lateral margins very lull, and curving rapidly to tlie ears. 



\'alves convex, the convexity e(|nal to one-fourtli tlic length of the hinge- 

 line. The right and left valves do not difler conspicuously in character, so 

 far as observetl. 



Hinge-line apparently straight, equalling nearly two-thirds the length of 

 the shell, central, not extending as far as either lateral margin. 



