306 Thirty-fifth Report on" the State Museum, 



actinopteria auriculata. 



Actinopteria auriculata, Hall. Pal. N. Y., vol. v, pt. 1. Unpublished. 



Shell small, rhomboidal ; body ovate, oblique at an angle of more 

 than 45° with the hinge-line ; length about one-fifth greater than the 

 height ; anterior margin rounded to the sinus ; base gently curved ; 

 posterior margin abruptly recurved. Left valve regularly convex 

 below, gibbous above. Right valve unknown. Hinge-line straight, 

 greater than the height of the valve. Beak anterior to the middle 

 of the hinge-line, acute, prominent, arching over the hinge. Um- 

 bonal region abruptly gibbous, subtending an acute angle. Ear 

 large, straight above, limited by an abrupt vertical byssal depres- 

 sion ; extremity rounded. Wing small, not strongly defined, join- 

 ing the body two-thirds of its length below the beak ; margin con- 

 cave ; extremity produced. 



Test marked by concentric striae, and about twenty somewhat' 

 strong, sharp radii ; this ornamentation is also continued on the 

 wing and the ear. 



The specimen is 10 mm. in length, 6 mm. in height, hinge-line 7 

 mm. 



This species resembles A. perstrialis in form, but differs in the 

 larger ear, abrupt vertical byssal depression, shorter wing and coarser 

 radii. 



Formation and locality. In the Chemung group at Lawrenceville, 

 Tioga county, Pa. 



Actinopteria delta. 



Actinopteria delta, Hall. Pal. N. Y., vol. v, pt. 1. Plates and Explanations: 

 PI. 23. fig 3. Jan., 1883. 



Shell of medium size, rhomboidal ; body broad-ovate, oblique at an 

 angle of about 60° ; height less than three-fifths the length ; an- 

 terior margin rounded, curving into a defined sinus ; base broadly 

 curved ; post-basal side abruptly rounded. Left valve gibbous 

 above, gently convex below. Right valve unknown. Hinge-line 

 straight, about equal to the height of the valve. Beak at about 

 the anterior third of the hinge, directed forward, prominent, rising 

 above the cardinal line. Umbonal region gibbous, nearly rectan- 

 gular. Ear rounded, defined by a distinct byssal depression which 

 extends forward from the beak. Wing small, joining the body 



