18 PALAEONTOLOGY OF NEW YORK. 



This spocit-s R'soiiiMcs A. rugastrialus in siirlaoe charactors, Imt it is less 

 obrujiu' and jjroportionally nuicli longer, with beaks more obtuse. The outline 

 of A. cancellatus is more nearly cireulju-, and the directiijn of the transverse 

 axis is <)bli(|ue. From A. scabridus it differs in its shorter hinge-line and 

 siiiidlfr ears, as well as in the surface markhigs. 



Formalion and localities. In tlie calcareous shales of the middle Chemung 



group, Ro{-k\ ille. Ilobbieville and Philipsburg, Alleghany county ; f^ast TJaii- 



<lolph, Cattaraugus county, N. V.: and Mansridd an<l Sullivan. Tioga county, 



Pennsylvania. 



AvirULOPECTEN CANCELL.\TUS. 



I'L.VTK vn, FIGS. 12, U-19. 



Pecten lancrllatiix. IIai.l. (Jeolofr. Siirv. N. V. : Rep. Fourth Dist. 184^. 

 Ncit Af'u-iiliijKctiii laiudUUidiut, McCoy. 



Peclru ffiilltanius,* i)'OnBt(;.vY. Pnxlrome ile Pala;ontolog'io, vol. I, i>. 87, No. 70S. 1847. 

 Avicidiiitecten mth-caiuxUatiui, H.\i.L. Pal. N. Y., vol. v, jit. 1. Plates ami Kx|ilanation.« : PI. 7, tijrs. 12, 



14-HI. .Jan., 1S,SS. 



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

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

 ears, gentl\ curving. 



Right valve regularly convex, slopmg 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, cros.sed by regular 

 sharp, concentric strise, producing an evenly cancellate surface. The 

 posterior ear is marked by the concentric strife with obscure radiating 

 lines; the anterior ear is rugo.se fn mi the prominence of from four to six 

 strong rays. 



*This name wa.s jii-opo.'OHl by il'Orbijfny as a HiiUntitute for Pecten faiu-ellalii.t, a name pi-eoccupieii l)y 

 Pliilli|H< foi- an Oolitir fotwil. The latter \h )n'o)>ably a true Pecten, ami there seems to me no sufficient 

 iTiuHiM why thi- on>,nnal name may not be retained. Avivula cauctllala, Phillips, Palaeozoic Fossils, is 

 probably not an Avienlolieeten. 



