9'2 PALAEONTOLOGY OF NEW YORK. 



PTERINEA TiNGlIS. 



PLATE XV, PIGS. -'. 8; LWD PLATE LXXX1II, FIG 13. 



Pteiinui pinffuia, Ball. Pal. N. V. vol. v, \>t. I. Plates and Explanations: PL 1">. tijrs. 2, 3. Jan.. 1S83. 



Shell large ; gibbous, obliquely ovate, length and height nearly equal. Pallial 

 margins rounded, produced on the posterior basal side, ami concave at the 

 junction of the wings. 



Left valve ventrieose, sub-angular along the anterior side. Right valve 

 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. Umbonal region prominent, 

 ventrieose, defined, subtending an acute angle. 



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

 valve ; margin slightly concave, rounding to the extremity which is angular. 

 The extent of the ear is not known, but it is limited by a deep sulcus which 

 gives an angular aspect to the antero-cardinal slope of the shell. Byssal 

 sinus not marked in the specimens. 



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

 by lamellae 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- 

 \cxitv of about 20 mm., length 63 mm., height 74 mm., hinge-line 55 mm: 



This species bears some general resemblance to P. fiabella; it differs in its 

 large ventrieose form, more elevated umbo, the characteristics of the upper part 

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

 distinct sulcus. 



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



