504 CRETACEOUS' PALEONTO'LOGY. 



Remarks. — Whitfield described this species from a single 

 specimen collected from the summit of the Wenonah sand near 

 Marlboro. It occurs in the recent collections of the Survey in 

 the same horizon at a neighboring locality, but seems to be a 

 rare form. A similar and perhaps identical species has been 

 recognized in the Cliffwood clay fauna at Cliffwood Point, which 

 differs from the Wenonah specimens chiefly in its much larger 

 size. 



Formation and locality.— ? Cliffwood clay, Cliffwood Point 

 (105) ; Wenonah sand, near 'Marlboro (130^). 



Geographic distribution.- — New Jersey. 



Genus ModioIvA Linneus. 



Modiola monmouthensis n. sp. 



Plate LV., Figs. 9-10. 



Description. — Shell small, the dimensions of an average speci- 

 men being: length, 8 mm.; width, 4.5 mm.; convexity of one 

 valve 2.5 mm. Hinge-line about one-half the total length of the 

 shell, beaks nearly anterior, incurved, umbo prominent; anterior 

 margin short and rounded, ventral margin nearly straight, 

 slightly sinuate back of the middle of the shell, posterior margin 

 rather sharply rounded below, sloping from the posterior ex- 

 tremity of the hinge-line above with a slightly convex curve. 

 Surface of the valves marked with fine radiating costse, which, 

 judging from the internal casts alone, are much stronger upon 

 the posterior portion of the shell ; surface also marked with con- 

 centric lines of growth. 



Remarks. — This species is the only member of the genus as 

 yet recognized in the Cretaceous faunas of New Jersey, in which 

 the shell is marked with radiating costse. It is also the smallest 

 species of the genus observed, none of the individuals varying 

 materially from the dimensions given above. 



Formation and locality. — Merchantville clay-marl, near Ma- 

 tawan (loi). 



Geographic distribution. — New Jersey. 



