MOLLUSCA. 571 



valve being characterized by a single cardinal tooth, which is 

 grooved on the surface, and by an anterior pit." (Whitfield.) 



Remarks, An illustration of this species was published by 

 Conrad as indicated above, but without name or description. 

 Whitfield found specimens in the collections of the Philadelphia 

 Academy of Science labeled "Cyclas cretacea" in Conrad's hand- 

 writing, and adopted Conrad's specific name, but Whitfield him- 

 self is the real author of the species. 



The species attains a much greater size at times, than is indi- 

 cated by Whitfield's illustration, the larger one of the specimens 

 figured by that author having a length of 16 mm. and a height 

 of 15 mm. The larger specimens from Lorillard are frequently 

 over 20 mm. in length. 



Formation and locality. Cliffwood clay, Cliffwood Point 

 (105), near Matawan (186) ; Woodbury clay, near Haddonfield 

 (164, 165, 183), Crosswicks (168), near Matawan (101), Loril- 

 lard (102); Red Bank sand, Shrewsbury River (116), near 

 Middletown (112). 



Geographic distribution. New Jersey, Alabama. 



Lucina swedesboroensis n. sp. 

 Plate LXIL, Figs. 19-21. 



Description. The dimensions of a small but nearly perfect 

 individual are: height, 13.5 mm.; length, 14 mm.; thickness, 

 6 mm. The dimensions of another left valve are: height, 14.5 

 mm.; length, 16 mm. The larger individuals sometimes attain 

 a height of 20 mm. Shell subcircular, varying from a little 

 higher than long to slightly longer than high. Beaks small, point- 

 ing forward. Valves depressed convex with a very obscure arcu- 

 ate umbonal prominence extending from the beak obliquely to 

 the postero-basal margin ; post-cardinal margin sharply inflected 

 to form a narrow and deep escutcheon ; in front of the beaks 

 the margin is sharply inflected to form a small but profound 

 lunule. Surface of the shell marked by rather fine, more or less 

 irregular concentric lines of growth. Hinge-line arcuate; hinge 

 of the left valve with a large, triangular cardinal tooth beneath 



