MIOCENE MOLLUSCA AND CRUSTACEA. 63 



men. The species, lidwever, can not be a true Mysia, as it has a broad pos- 

 terior hiuge ])late, a thickened shell, and nitich larger muscular scars than 

 exist in shells ot" that yeuus. It appears to me to be nmch nearer the true 

 Lucina\ 



The shell, so tar as can be ascertained from the t'raoinent, is circular iu 

 outline, or nearly so; only moderately convex and uuich thickened in sub- 

 stance; outer surface with thickly crowded, hxinellose, concentnc lines, and 

 a posterior sulcus moderate!}' well marked. In the interior the hing-e plate 

 is wide behind the beak, and the posterior lateral tooth obsolete: nuiscular 

 scar on the posterior side moderately large, and bordered by a deep sulca- 

 tion coiTesponding to the sulcus on the exterior. 



Local if//: The specimen is among the shells from Shiloh, N. J.; and 

 belongs to the collections of the National Museum at Washington, D. C. 



. LuniNA CKENULATA. 



Plate X, tigs. 7-15. 



Lucina crenulata Conrad; Miocene Foss., p. 39, PI. xx, fig. 2; Proc. Acad. Nat. Sci. 



Phil., 1862, p. 577; Meek, Check List, p. 8; Tuoiney and Holmes, Plioc. Foss. 



S. C, p. 60, PL XVIII, ag. 14; Heilprin, Proc. Acail. Nat. Sci. Phil, 1887, p. 403. 

 Compare L. lens H. C. Lea: Trans. Am. Phil. Soc, vol. !», p. 14, PI. xxxiv, fig. 19. 



"Shell lenticular, with numerous concentric iaminti?; a submarginal 

 fold on the posterior side; posterior extremity truncated; cardinal line 

 straight, oblique; beaks central; cardinal and lateral teeth distinct; margin 

 minutely crenulated." (Conrad.) 



The larger individuals of this species which I have seen from the 

 Miocene beils of New Jerse}- do not exceed one-fourth of an inch in diam- ■ 

 eter. The shell is subcircular in outline, moderately ventricose and deeply 

 excavated in front of the small, pointed and sul)central beaks. The surface 

 of the valves is strongly lamellose with faint radiating stria', coiTesponding 

 to the crenulations on the inner margins of the shell. The features of the 

 interior are distinct, especially the lateral teeth, which are proportionally 

 strongly develo]ied, and the nuiscular scars very well marked. In very 

 many of the shells the radiating striae are distinctly marked on the interior 

 of the valves. 



