92 PALEONTOLOGY OF NEW YORK. 



PtEKINEA I'INGUIS. 



PLATE XV, KIGS. ■->, 3; AND I'l.ATE LXXXIII, KIG 13. 



Pterinea piiiguii. Hall. Pal. N. Y, vol. v, pt. I. Pliiti's mid Kxiihiiuitiiins : PI. 1."), Kj^s. 2, ',i. Jan., 1S83. 



Shell large; gibbous, obliquely ovate, length ami lieigiit nearly equal. Pallial 

 margins rounded, produced i>n the posterior basal side, and eoneave at the 

 junction of the wings. 



Left valve ventricose, sub-angular along the anterior side. Right \al\e 

 unknown. 



Hinge-line straight, nearly central ; length somewhat greater than the 

 length of the shell. 



Beak acute, angular, arching over the hinge, situated near the anterior 

 extremity of the hinge-line, directed forwards. Uinl)onal region prominent, 

 ventricose, defined, subtending an acute angle. 



Wing large, triangular, limited by the rapid post-cardinal slope of the 

 valve ; margin slightl\' concave, roimding to the extremity which is angular. 

 The extent of the ear is not known, but it is limited by a dec]) sidcus which 

 gives an angular aspect to tlu^ antero-cardinal sloi)e of the shell. Byssal 

 sinus not marked in the specimens. 



Surface ornamented with about fifteen broad, strong, rounded rays, crossed 

 by lamellge of growth. The specimens described are weathered casts of the 

 interior and preserve only slight evidence of the surface characters. 



Interior not known. 



The largest specimen has a convexity of about 20 mm., its length 7(1 mm., 

 height 65 mm., hinge-line more than 65 mm. Another example has a con- 

 vexity of about 20 mm., length 6.^ mm., height 74 mm., hinge-line 55 mm. 



This species bears some genei'al resemblance to P. Jiabella ; it differs in its 

 large ventricose form, more elevatctl umbo, the characteristics of the ui)per part 

 of the anterior side of the body, and the abrupt slope into the wing without a 

 distinct sulcus. 



Formation and locality. In the Corniferous limestone, near Columbus, Ohio, 



