18 PALEONTOLOGY OF NEW YORK. 



This species resembles A. rugccstriatus in surface characters, but it is less 

 oblique and proportionally much longer, with beaks more obtuse. The outline 

 of A. cancellatus is more nearly circular, and the direction of the transverse 

 axis is oblique. From A. scabridus it differs in its shorter hinge-line and 

 smaller ears, as well as in the surface markings. 



Formation and localities. In the calcareous shales of tin' middle Chemung 

 group, Rockville, Hohhieville and Philipsburg, Alleghany county ; East Ran- 

 dolph, Cattaraugus county, N. Y. ; and Mansfield and Sullivan, Tioga county, 

 Pennsylvania. 



A.VICULOPECTEN CANCELLATUS. 



PLATE VII, FIGS. IS, u-1'.' 



Pecten cancettatus. Hall. Geolog. Suit. N. V. : Rej>. Fourth Dist. 1843. 

 Not AvictUopecten canceilatulus, McCoy. 



Peeteu Hdlleanu*,* d'Orbiqnt. Prodrome de Pabsontologie, vol. I. p. 87. No. 768. 1847. 

 Avicnlopecten fmb-caiicellatu.1. Hall. Pal. N. Y.. vol. v, pt. 1. Plates ami Explanations: PI. 7. figs. 12, 



14-19. Jan.. 1883. 



Shell small, broadly ovate, oblique, height a little greater than the length; 

 anterior lateral margin full and rounded ; posterior lateral margin, below the 

 ears, gently curving. 



Right valve regularly convex, sloping somewhat abruptly to the posterior 

 ear. 



Hinge-line straight, equal to two-thirds the length of the shell. 



Beaks, anterior to the middle of the hinge-line, well-defined, obtuse. 



Posterior ear small, undefined, the lateral margin concave, not projecting. 

 Anterior ear marked by a deep sinus, with a sulcus extending to the beak : 

 lateral margin rounded. 



Test marked by fine, regular, rounded, radiating lines, crossed by regular 

 sharp, concentric, stria 1 , producing an evenly cancellate surface. The 

 posterior ear is marked by the concentric striae with obscure radiating 

 lines; the anterior ear is rugose from the prominence of from four to six 

 strong rays. 



♦This name was proposed by d'Orbigny as a substitute for Pecten cancellatus, a name pi ecupied by 



Phillips for an Oolitic fossil. The latter is probably a true Pecten, ami there seems to me no sufficient 

 reason why tin' original name maj not be retained. Avicttla cancellata, Phillips, Palsozoic Fossils, is 

 probablj not an Aviculopecten. 



