MARINE MOLLUSCA OF THE UNITED STATES. 171 



Genus ZELLIA, Turton. 

 Brit. Bivalves, 57. 1822. 



The animal has a very short posterior siphon : anal tube undi- 

 vided, entire below. 



1. K. planulata, Stirupson. Fig. 432. 



Shells of New Eng., 17. 1851. 

 Eellia rubra, Gould (not Montagu), Invert. Mass., edit. i. 60. 1841. 



Shell minute, rather thick, suboval ; beaks prominent, in contact, 

 with a well-defined lunule in front of them ; anterior, white, with 

 a thin purplish epidermis. 

 Length 4, height 3 mill. 



New England. 



More compressed and longer than the next species. 



2. K. suborbicularis, Montagu. Figs. 433, 434, 435. 



{My a.) Test. Brit., 39, 564, t. 26, I 6. 1803. 



Shell quadrangular or rounded, swelled, thin and fragile; white 

 with a very thin somewhat iridescent epidermis ; beaks nearly 

 median, small, pointed, inclining inwards rather than forwards; 

 no lunule. 



Length and height 8 mill. 



New England. (N.Eur.) 



Genus TTJKTONIA, Hanley. 

 Brit. Moll., ii. 81. 1849. 



Anal siphon slender and produced. Foot large, heeled. 



1. T. nitida, Verrill. Figs. 438, 439. 



Am. Journ. Sci., iii. 286, t. 7, f. 4, 4a. 1872. 

 T. minuta, Gould (not Fab.), Invert. Mass., edit. ii. 85, f. 395. 1871. 



Shell minute, ovate, rather convex, fragile, semitransparent, 

 beaks at about the anterior third, elevated, inclined forwards ; 

 smooth, straw-colored, blending into dark-purple at the beaks and 

 posterior slope ; anterior margin broadly rounded, posterior 

 margin more acutely rounded. 



Length 2, height 1.7 mill. 



Found in crevices of shells and rocks, and among the roots of 

 sea-weeds. 



Northern Coast. 



