I NYE LiTEIi RATE TA L7EONTOL< X i Y. | i ', 7 



hinge provided with two diverging cardinal teeth in each valve (the anterior 

 being somewhat extended horizontally), but without lateral teeth; muscular 

 impressions shallow, not elongated; pallial line simple. 



This genus is distinguished from Coib'is bv its want of lateral teeth, as 

 well as by its more globose form, and smoother surface. It seems to have 

 been introduced during the Triassic period, and occurs in the Jurassic, from 

 which latter the typical species was obtained. Its existence during the 

 deposition of the Cretaceous rocks is not yet positively determined; though 

 we meet with imperfectly-known forms in rocks of that age, that are referred 

 provisionally to it, until specimens can be found showing their generic 

 characters. Its reference to the Luc/ii'dte is only provisional. 



s i> 1 1 : r ■- ■ ii I :i ! cordata, M. & H. 



Plate 29, figs. 3, a, b, c. 



Cyprina cordata, Meek and Hayden (1857), Proceed. Acad. Nat. Sci. Pbilad., IX, 143. 

 Bucardial Moreauensis, Meek and Hayden (1860), ib., XII, 427. 

 (iliismisl Moreauensis, Gabb (1861), Cat. Cret. Fossils, 125. 



Shell thick, globose, very gibbous, higher than long; sides and base 

 rounded ; beaks elevated, pointed, and curved somewhat obliquely forward 

 and inward, very nearly central; muscular impressions broad-oval, faintly 

 marked ; pallial line distinct and forming a regular curve, parallel to the base, 

 in passing from the anterior to the posterior muscular scars. Surface with 

 distinct concentric striae, and stronger marks of growth. Hinge unknown. 



Length, about 1.66 inches; height, 1.80 inches; convexity, 1.50 inches. 



The unsatisfactory condition of the only specimen of this shell yet seen 

 renders the determination of its generic characters very difficult and uncer- 

 tain. Being mainly an internal cast with portions of the shell attached, it 

 gives little or no idea of the nature of the hinge, beyond the fact (recently 

 determined by the removal of some adhering portions of the shell about the 

 hinge) that it has no lateral teeth. The muscular impressions, as left on 

 internal casts, are also seen to be very shallow and not elongated, and the 

 pallial line to be certainly simple. In first indicating it, we thought that 

 possibly it might be a gibbous form of Cyprina, and referred it, as stated at 

 the time, provisionally only, to that genus. Subsequently, feeling quite con- 

 vinced that it at least could not be properly retained in the genus Cyprina, we 

 removed it, with a mark of doubt, to the genus Bucardia, mo>-° properly 

 18 H 



