MOLLUSCA. 637 



curve to the anterior and ventral margins, and more gently to the 

 postero-basal extremity; each valve with an angular umbonal 

 ridge, that of the left valve much the more conspicuous; post- 

 umbonal slope of the right valve narrow, slightly concave, in- 

 flected to the hinge-line towards the beak; that of the left valve 

 much broader, concave, sloping much more abruptly, not in- 

 flected. Surface of the right valve marked by rather regular, 

 moderately fine, rounded, concentric costae, which seem to ter- 

 minate at the umbonal ridge ; the left valve marked by more or 

 less irregular concentric lines of growth which are not raised 

 into distinct, rounded ribs, and on the anterior portion of the 

 valve by a few indistinct radiating costse. 



On the internal casts the surface is smooth, the muscular im- 

 pressions are indistinct, and the beaks are widely separated and 

 erect. The general form and contour of the valves is the same. 



Remarks. The specimens which have been used in the de- 

 scription of this species were collected by Mr. John M. Manley, 

 of New Brunswick, at Furman's clay pits, Sayreville, New Jer- 

 sey. They are of special interest because they were collected 

 from near the base of the Raritan formation, at a horizon which 

 has rarely yielded invertebrate fossils. The species is a very 

 peculiar and distinct one, and is quite different from any other 

 Corbula in the faunas of the New Jersey Cretaceous beds. 



Formation and locality. Raritan formation, Sayreville. 



Geographic distribution. New Jersey. 



Corbula lorillardensis n. sp. 

 Plate LXXIL, Figs. 9-14. 



Description. The dimensions of an internal cast are: length, 

 10.5 mm.; height, 5.5 mm; thickness, 4 mm. Shell elongate 

 subovate in outline, broader in front than behind ; the beaks 

 central or a little in front of the center, broadly obtuse, a little 

 incurved ; right valve overlapping the left along the ventral mar- 

 gin. Anterior and posterior cardinal margins sloping downward 

 in front and behind the beak, meeting at an angle of about 142 ; 

 anterior margin regularly rounding from the cardinal into the 

 basal margin; basal margin long, gently convex; postero-basal 



