220 Monograph of the Lamellihranchiata. 



high, cuneate posteriorly, and more convex in the central and anterior 

 regions, with a slight concavity descending from the beak to the base 

 of each valve; posterior margin regularly rounded; base straight, and 

 parallel to the cardinal margin in the middle, and rounding up to the 

 anterior and posterior margins; anterior side short, rounded or some- 

 what truncated, but apparently most prominent below ; hinge line 

 shorter than the valves, straight behind the beaks, but rounding into 

 the posterior margin at the extremity, erect behind, with some appear- 

 ance of a narrow space for an external ligament farther forward ; beaks 

 about one fourth the length of the valves from the anterior margin, 

 raised a little above the cardinal margin, nearly contiguous, but not 

 much incurved. Surface of a cast, that seems to be a little weathered 

 or smoothed by attrition, showing obscure marks of growth. Length, 

 0-77 inch; height, 059 inch; convexity, 0'29 inch. 



Found at the quarries back of Cincinnati, about 350 feet above low 

 water-mark. Range unknown. 



Scdgwiclda (^Grammy da?) N'eghcki — (Meek). 



Shell transversely ovate, about one third longer than high, rather 

 distinctly compressed, most convex and most elevated in the central 

 and umbonal regions, and compressed-cuneate behind ; anterior margin 

 rounding from the lower end of the lunule into the base, which forms 

 a nearly semi-oval curve, its most prominent part being near the mid- 

 dle ; cardinal margin apparently straight, and declining posteriorly 

 from the beaks ; posterior margin rather narrowly rounded ; beaks 

 moderately prominent, and scarcely one third the length of the valves 

 from the anterior margin. Surface ornamented with regular, distinct, 

 but not very prominent concentric costie, that become suddenly obso- 

 lete on the posterior third of the valves. Lunule narrow, but sharply ^ 

 defined. 



Length, about 1-04 inch; height, 0*67 inch ; convexity about 0-.35 

 inch. 



Found in the upper part of the Cincinnati Group, in Clinton county. 



ft 



Cardiomorpha f f ohiiquata — (Meek). 



Shell small, rhombic-cordate, veiy convex, higher than long ; pos- 

 terior margin sloping rather abruptly, and subtruncate, or a little con- 

 vex in outline from the posterior extremity of the hinge to the pos- 

 terior basal extremity, which is more or less angular, or narrowly 

 rounded; basal margin short, nearly straight or a little convex from 



