248 MARINE SHELLS OF THE UNITED STATES. 



also marked with the black line, but there is only 

 a circumscribed callous extending laterally, leaving 

 a large umbilicus, and marked transversely by a 

 groove. 



I formerly referred this species to .TV*, rugosa, but 

 it appears to be a much larger species, as Dillwyn 

 states the rugosa to be only ten lines long. It is 

 probably the same species as that represented by 

 Lister on plates 562 and 563, but 1 do not find those 

 figures referred to at all by Dillwyn. 



2. N. *heros. Shell suboval, thick, rufo-cinere- 

 ous ; within whitish ; columella incrassated ; callous 

 not continued over the upper part of the umbilicus, 

 hardly extending beyond a line drawn from the base 

 of the columella to the superior angle of the labrum ; 

 umbilicus free, simple. 



Length about two inches and a half. 



Inhabits the coast of New Jersey. 



I have two specimens from Great Egg Harbour. 

 It differs from the preceding species in being less 

 dilated, destitute of the black line of the apex, and 

 of the much incrassated projection from the columel- 

 la so conspicuous in that shell. This is our largest 

 species. I have a specimen more than three inches 

 in length. 



I formerly considered this to be the J\T. rufa, 

 Gmel. but that species is said by Dillwyn to be only 

 half an inch or au inch long, and he refers to Born, 

 t. 17, f. 3, and 4, and also to Lister, Conch, t. 506, 

 f. 3, neither of which figures resemble our species. 



[to be continued.] 



