218 Monograph of the Lamellihranchiata. 



tain that it belongs to the genus Modiolopsis. It is very scarce, a good 

 specimen ornamenting but few cabinets. It is occasionally found at 

 the quarries back of Cincinnati, from 300 to 450 feet above low water- 

 mark. 



Genus Cypricardites — (Conrad). 



[See page 147, April No. of this Journal.] 



Cypricardites Hainesi — (S. A. Miller.) 



[See page 147, April No. of this Journal.] 



Since this description was Avritten, I have spent two days at Rich- 

 mond, Indiana, and succeeded in finding valves with the cardinal teeth 

 preserved. There are two cardinal teeth (at t, Fig. 13), rather obtuse, 

 width a little greater than the length. 



Cypricccrdites Sterlingensis — (Meek and Worthen). 



Shell obliquely rhoraboidal, or rhombic subcordate, being cordate 

 in outline as seen in an anterior or posterior view, and more or less 

 rhomboidal as seen from either side. Posterior margin very obliquely 

 truncated, Avith a long slope ; posterior basal extremity produced and 

 very narrowly rounded ; basal margin ascending forward with a mod- 

 erately convex curve, and rounding upward into the very short, more 

 or less rounded, anterior margin. Hinge line short, ranging at an angle 

 of about 45 to 50 degrees from the umbonal axis. Umbonal ridges 

 very prominent, or subangular, from the posterior side of the beaks 

 obliquely backward and downward to the posterior basal extremity ; 

 area above and behind this ridge, flattened in each valve ; and that 

 below arid in front of it more or less convex. Surface unknown. 

 Posterior muscular impression large, nearly circular, faintly marked, 

 and placed near the middle of the posterior truncated margin. An- 

 terior muscular scar smaller, more oval, and placed nearly against the 

 anterior margin. 



liength, measuring obliquely from the most prominent part of the 

 front to the posterior basal extremity, 2.14 inches ; height at right 

 angles to the hinge, 1.75 inches ; convexity, 1.25 inches. 



Found in the upper part of the Cincinnati Group, at Richmond, 

 Indiana. 



Cypricai'ditesf carinata — (Meek). 



Shell small, rhombic-cordate, very convex along the oblique umbonal 

 slopes, posterior margin apparently obliquely truncated ; posterior basal 



