\2-2 PALEONTOLOGY OF NEW YORK. 



Lfl't valvL- iiiljhuiis abovt.', gently convex below. Ki^ht valve uuknowu. 



Hinge-line straight, abont equal to the height of the valve. 



Beak at about the anterior third of the liini:f. directed forward, ]in)iiiinent, 

 rising above the cardinal line I'lnbonal region giljbous, iicarlv rectangular. 



Ear rounded, defined by a distinct Inssal depression wbich extends 

 forward from the l)eak. Wing small, joining the bod}- near the posterior 

 extremity, not strongly defined ; margin gently concave ; extremity produced. 



Test marked by fine concentric striae, and undulating or interrupted 

 filiform radiations, with wider interspaces, which have probably been marked 

 by finer intermediate striae. The concentric lines are obscure in the cast 

 and appear as a few irregular concentric undulations. 



Interior unknown. 



The specimen is 23 mm. in length, 1;") mm. in height, hinge-line 16 mm. 



Formation and locality. In the lower part of the Chemung group at Ithaca, 

 N. Y. 



ACTINOPTERIA EPSILON. 



I'LATE XXni, FIGS. 4, », (5 ami li?). 



Arli/ii/plrna iiisiliiii. ILm.i,. P;il. N. Y., vol. v, pt. 1. Plfttes and Explanation.^: PI. 23, tigs. 4, 8. .Jan., 1883. 



Shell of medium size, rhondioidal : body ovate, oblique to the axis at an angle 

 of about Cid'^ ; height about three-fourths the length ; anterior margin rounded 

 into a very abrupt sinus; l)ase broadly curved; post-basal side abruptlv 

 rounded. 



Left valve moderately convex. Right valve depre.ssetl-convex above. Hat 

 or concave below. 



Hinge-line straight, length somewhat less than the liiigbt of the valve. 



Beaks anterior, acute in the left valve; prominent and elevated aliove the 

 hinge. Umbonal region gibbous, subtending an angle of less than GO'-'. 



Ear short, defined by a deep, abrupt byssal depression. Wing trianguhir, 

 joining the body below the middle, not strongly defined ; margin regularly 

 concave ; extremity acute and produced. 



