MIOCENE MOLLUSCA AND CRUSTACEA. 63 
men. The species, however, can not be a true Mysia, as it has a broad pos- 
terior hinge plate, a thickened shell, and much larger muscular sears than 
exist in shells of that genus. It appears to me to be much nearer the true 
Lucine. 
The shell, so far as can be ascertained from the fragment, is cireular in 
outline, or nearly so; only moderately convex and much thickened in sub- 
stance; outer surface with thickly crowded, lamellose, concentric lines, and 
a posterior sulcus moderately well marked. In the interior the hinge plate 
is wide behind the beak, and the posterior lateral tooth obsolete; muscular 
scar on the posterior side moderately large, and bordered by a deep sulca- 
tion corresponding to the sulcus on the exterior. 
Locality: The specimen is among the shells from Shiloh, N. J.; and 
belongs to the collections of the National Museum at Washington, D. C. 
LUCINA CRENULATA. 
Plate x, figs. 7-15. 
Lucina crenulata Conrad; Miocene Foss., p. 39, Pl. xx, fig. 2; Proc. Acad. Nat. Sci. 
Phil., 1862, p. 577; Meek, Check List, p.8; Tuomey and Holmes, Plioe. Foss. 
8. C., p. 60, Pl. xvi, fig. 14; Heilprin, Proc. Acad. Nat. Sci. Phil., 1887, p. 403. 
Compare L. lens H. C. Lea: Trans. Am. Phil. Soe., vol. 9, p. 14, Pl. xxxtv, fig. 19. 
“Shell lenticular, with numerous concentric lamin; 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 beds of New Jersey 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 subcentral beaks. The surface 
of the valves is strongly lamellose with faint radiating strie, corresponding 
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 developed, and the muscular scars very well marked. In very 
many of the shells the radiating strize are distinctly marked on the interior 
of the valves, 
