LAMELLIBRANCHIATA. 435 



LUNULICARDIUM MaRCELLENSE. 



PLATE LXXI, FIGS. 15, 16. 



Oypricardites MarcellensU, Vanuxbm. Geol. Surv. N. Y., Rep. Third Dist., p. 147, t. 35, fig. 4. 1842. 

 Lunitlicardium Marcelltnse, " Hall. Prelim. Notice Lamellibranchiata, 2, p. 97. 1870. 



" " " " Pal. N. Y., vol. V, pt. 1. Plates and Explanations : PI. 71 



figs. 15, 16. 1883. 



Shell of medium size, somewhat obovate, truncate behind; length a little 

 greater than the height. Anterior and basal margins regularly curved. Pos- 

 terior slope obliquely truncate. 



Valves moderately convex below, becoming gibbous in the upper portion. 



Beaks anterior to the middle of the length, erect. 



Test of moderate thickness. Surface marked by fine, closely arranged 

 concentric striae. In exfoliated specimens there are indications of radii 

 which are often more distinctly marked along the margin of the valve. 



Three specimens measure respectively 30, 35 and 36 mm. in length, and 

 32, 33 and 33 mm. in height. 



This form differs somewhat from the figure given by Mr. Vanuxem, and a 

 specimen corresponding, in form, to his figure, shows a few distinct plications 

 upon the upper anterior margin of the shell. The material in hand is very 

 unsatisfactory, and better collections may lead to a separation into two distinct 

 species. 



Formation and localities. In the Marcellus shale of Cherry Valley, Sharon 

 Springs and Schoharie, N. Y. 



LUNULICARDIUM RUDE. 



PLATE LXXI, FIG. 17. 



LunvXicardium rude. Hall. Pal. N. Y., vol. v, pt. 1. Plates and Explanations : PI. 71, fig. 17. 1883. 



Shell of medium size, obovate, obliquely truncate on one side ; length and 

 height nearly e^iual. Anterior and basal margins regularly curving. Post- 

 cardinal slope obli(iuely truncate ; margin thickened and deflected. 



