346 SYSTEMATIC PALEONTOLOGY 



The much greater flatness of the shell, the absence of granulations 

 on the ribs except very near the nmbo, the very slight convexity of the 

 ribs themselves giving the surface an almost smooth appearance, as 

 well as the number of the ribs, readily distinguish this species from 

 any of the Maryland specimens of Venericardia granulata. 



Length, 20 mm.; height, 21 mm.; diameter, 4.5 mm. 



Occurrence. — Calveet Foemation. Church Hill, Eeed's. 



Collections. — Maryland Geological Survey, Johns Hopkins University. 



Superfamily ASTARTACEA. 

 Family CRASSATELLITID/E. 



Genus CRASSATELLITES Kruger. 



Ceassatellites melinus (Conrad). 

 Plate XCII, Figs. 1, 2. 



Crassatella melina Courad, 1833, Fossil Shells of the Tertiary, p. 33, pi. ix, fig. 3. 

 Crassatella melina Conrad, 1838, Fossils of the Medial Tertiarj-, p. 33, pi. xii, fig. 3. 

 Crassatella melina Conrad, 1863, Proc. Acad. Nat. Sci. Phila., vol. xiv, p. 578. 

 Crassatella melina Meek, 1864, Miocene Check List, Smith. Misc. Coll. (183), p. 7. 

 Crassatella melina Whitfield, 1894, Mon. xxiv, U. S. Geol. Survey, p. 60, pi. viii, 



tigs. 11-13. 

 Crassatellites [Scamhnla] melinns Dall, 1903, Trans. Wagner Free Inst. Sci., vol. iii, 



pt. vi, p. 1473. 



Description. — " Ovate, thick, not compressed; anterior margin ob- 

 tusely rounded; posterior margin oblique and angular; dorsal margin 

 nearly straight; concentric lines coarse; umbonial slope subangular and 

 scarcely curved; beaks with concentric grooves; inner margin entire." 

 Conrad, 1832. 



This species, as found in Maryland, is more properly described as 

 subovate, convex-depressed, and rather thin except in old specimens, 

 which are somewhat thicker and more convex. It is somewhat more 

 produced posteriorly and hence is proportionally narrower along the 

 obliquely truncated posterior margin than is represented in Conrad's 

 figure. The dorsal slope has regular, well marked, angular, concentric 

 undulations near the beak that become obsolete during later stages of 

 growth; posterior and dorsal slopes separated by a distinctly angular 

 line; posterior slope somewhat flattened; posterior dorsal margin but 



