26 PALEONTOLOGY OF NEW YORK. 



Ears Pub-equal, Iji-oad-triiiiiixulur, flat ; marffins slij;litly convex; extromitios 

 R'ctanjiular, (k-liiieil In a gcntlu .sinus, wliic-h is dfi'per helow the anterior ear. 



Test niarke<l liy aljout 35 strong, rounded, radiating continuous plications 

 which are wider than the interspaces. These radii are absent on the ears. 

 The stria? of growth are irregular and niaik tlie entire surface of the shell. 



Internal characters not observed. 



A large specimen has a height of 53 mm., length 06 mm., hinge-line 34 mm. 



This species differs from A. patulus in its shorter hinge-line, and the strong 

 rounded radiating plications. 



Formation and locality. In sandstone of the upper part of the Chemung 

 group at Meadville, Crawford county, Pennsylvania. 



AviCULOPEC'TEN D0LA15IUF0KM1S. 

 PLATE VII, KIG.il. 



Pecten) dohrhrifurmh, Hall. Geoli>{r. Suiv. N. Y. : Rep. Fourth Dist., p. 2ti.'). 1843. 

 Avitndoptvteii dulabrifonni.s. Hall. Pal. N. Y., vol. v, pt. 1. Plates and Explanations : PI. 7, tijf. 21. 



Jan., 1883. 



Shell small, .-^iil)-nrliicular, slightly olilicpie; lieight nearly equal to the length; 

 margins regularh iDuiided, becoming more inflated and convex posteriorly. 



Right valve moderately convex. Left valve unknown. 



Hinge-line straight, central, more than two-thirds the length of the shell. 



Beak central, straight, obtuse, rounded, not rising above tlie hinge-line; 

 iiiulx) well ilefiiied by the rapid slope of the sides and the tiatness of the 

 ears. 



Ears triangular. Hat; margins slightly concave; extremities obtuse-angular. 

 Posterior ear of the right valve about one-third larger than the anterior. 

 Byssal sinus not marked. 



Test cancellate, marked li\ line radii and eoneeiitric stria', wiiicli cliai- 

 acters are also preserved on the ears. 



Internal characters not known. 



A right valve has a height of 11 mm., length 12 mm., and hinge-line 8 mm. 



