1874.] 253 [Rathbun. 



Family LUCINIDiE. 



Irucina tenella sp. nov. 



Sliell very small and lenticular, with the length slightly greater 

 than the height. Valves moderately convex. 



The beaks are small, not at all prominent, are situated near the 

 middle of the shell and incline slightly forward. The margins of the 

 valves, so far as can be determined from their imperfect condition, 

 form nearly a circle, truncated slightly at the hinge. Anteriorly the 

 shell is produced a little upward, nearly as high as the beak, the 

 hinge margin forming in front of the beaks a slight inward curve, 

 and then ascending a little to the upper anterior angle. The hinge, 

 posterior to the beaks, is apparently straight and descends moderately 

 toward the posterior extremity. 



Valves most convex just above the middle. The surface curves 

 moderately from the beaks to the ventral margin, the curvature de- 

 creasing gradually in strength downward. Along the antero-poste- 

 rior diameter the curvature is gradual and regular. The upper pos- 

 te ; ior portion of the shell becomes suddenly slightly compressed from 

 along a line extending from behind the beaks to a short distance be- 

 low the middle of the posterior margin. This compressed portion 

 forms a rather narrow crescentic space, bordering the margin. 



The surface is marked with very fine, regular, slightly overlapping, 

 concentric raised lines of growth, those near the beaks being often 

 quite faint; but they become gradually coarser toward the mar- 

 gin. On the posterior depressed space they are deflected slightly 

 upward. The interspaces are very much broader than the lines and 

 are flattened, and all of about equal width. The muscular imprints 

 are not preserved in the mould. 



From the cretaceous limestone bed at Maria Farinha, Prov. of 

 Pernambuco, Brazil. Only two specimens have been obtained. 



Family CARDLAJX2E. 



Cardium Soaresanum sp. nov. 



Shell small, gibbous, subquadrangular in outline, and with the 

 antero-posterior and vertical diameters nearly equal. The depth of 

 the two valves equals about two-thirds or three-fourths the antero- 

 posterior diameter. The hinge is nearly as long as the shell, and 

 rounds very rapidly into both the anterior and posterior margins, the 



