LAMELLIBEANCHIATA OF THE LOWER MAELS. 47 



Pecten quinquenarius. 

 Plate VII, Figs. 13-16. 

 Pecten quinquenaria Con. J. A. X. S., Phil., Vol. IT, p. 275, PI. XXIV, Fig. 10, 1854. 



Shell of medium size, slightly oval transversely; in outline a little 

 wider than high. Valves plano-convex in profile when united. Hinge hne 

 much shorter than the width of the shell below. Ears large, slightly un- 

 equal; that of the flat valve (right) somewhat sinuate on the anterior side. 

 Cardinal slope of the valves somewhat concave between the beaks and the 

 lateral margins of the body of the shell. Surface of the valves marked by 

 strong, wide, rounded, radiating ribs, about five on the flat valve and six on 

 the convex valve. On the convex valve, as shown upon the impression 

 left in the fine blue marl, there have been fine, even, and closely arranged 

 concentric lines crossing the folds and passing up over the auriculations ; 

 in fact, covering the entire surface of the valve. The opposite flat valve 

 has not been marked by concentric lines, as was the convex valve, the sur- 

 face of the cast, both inside and outside impressions, being apparently 

 smooth. No remains of radiating lines on the folds can be seen. 



There can be no question as to the identity of the New Jersey shells 

 here figured and described with the specimen from Delaware used by Mr. 

 Conrad in his original description, although our specimens show the folds 

 comparatively broader than does his figure. Mr. Conrad's description is 

 very imperfect, and leaves one in doubt as to most of the features of his 

 shell, as he states only that it is ''ovate, much compressed, with five distinct 

 ribs, broad and rounded on one valve, narrow and subangulated on the 

 opposite valve. (A cast.)." 



Formation and locality. — In the lowest beds of tlie dark-blue marl of the 

 Lower Green Sands at G.C. Schanck's pits, Marlborough, New Jersey. The 

 only two specimens seen are casts, but the fine marl preserves the surface 

 features of the shell in a remarkable degree of perfection. 



Pecten tenuitestus. 



Plate VII, Figs. 5 and 6. 



Pecten tenuitesta Gabb. Proc. A. X. S., Phil., 18GI, p. 327. Meek, Check-list, Smith. 

 Inst., p. 7. Geol. Eept. X. J., 1868, p. 725. 



Shell of small to medium size, broadly ovate exclusive of the auricu - 

 lations, the breadth of the shell being to the height as six is to seven. 



