LAMELLIBEANCHIATA OF THE LOWER MARLS. 167 



Linearia contracta, u. sp. 

 Plate XXIII, Fig. 5. 



Shell small and moderately convex, transversely ovate in outline, broad 

 in front and abruptly contracted behind the beaks, the anterior end forming 

 about three-fifths of the shell's length. Beaks small and inconspicuous. 

 Anterior end broadly rounded and the posterior more narrowly rounded. 

 Basal line broadly curved. Surface of the shell as seen in a matrix, marked 

 by fine radiating strise which extend over the entire surface, but are less 

 strongly developed on the middle of the valve. Also marked by fine con- 

 centric grooves parallel to the margin of the shell. 



This species differs from L. metastriata in being proportionally longer, 

 in the abrupt contraction of the posterior end, in its ovate instead of oval 

 form, greater convexity, and in being marked by radiating strise througlioiit 

 instead of having the central part of the valve nearly or quite destitute of 

 this marking. 



Formation and locality. — In dark micaceous clay marls at the base of 

 the Lower Marls, at Holmdel, New Jersey. 



Genus .^ORA Courad, 1871. 

 (Am. Jour. Couch., Vol. VI, p. 72, 1871.) 



.Slora cretacea. 

 Plate XXIII, Figs. 16 and 17. 

 JEora cretacea Conrad. Am. Jour. Conch., Vol. VI, p. 72, PI. Ill, Pig. 8. 



Shell small or below a medium size, longer than high, and subtriangu- 

 lar or triangularly elliptical in outline. Valves convex, with small sub- 

 central beaks, which are nearly opposite the middle of the valves; cardinal 

 margins sloping from the beaks at nearly an equal angle on the opposite 

 sides, and forming with each other an angle of about one hundred and 

 twenty degrees, the anterior side a little excavated in front of the beak. 

 Anterior margin of the valve more sharply rounded than the posterior, and 

 the basal line broadly curved. Surface of the shell marked by irregular 

 concentric lines of growth only. 



