220 BELA. 



ribs, usually lower spire, finer spiral sculpture, etc. Towards its 

 northern limit it becomes rather rare, according to Prof. Yerrill. 

 Sars' figure of B. harpularia appears to represent a variety of 

 B. turricula. 



B. AMERICANA, Packard. PI. 33, fig. 64; PI. 29, fig. 68. 



Shell thin, inflated, body-whorl rather wide, spire short; 

 shoulder strongly defined, with the ribs crossing it ; ribs 13 to 15, 

 rather high and narrow, somewhat oblique, with wider inter- 

 spaces ; revolving sculpture very distinct on the interspaces, 

 less distinct on the ribs ; whitish or yellowish white. 



Length, 18-20 mill. 



Cape Cod to Greenland. ? Norway. 



The shell figured by Sars as B. nobilis, Moller, juv. (fig. 42) 

 appears to = this species, but fig. 19 in the Moll. Norv. better 

 represents B. turricula. The shell very usually occurs under 

 the latter name in American collections, but appears to differ 

 sufficiently in its shorter, wider form, thinness, etc. B. turricula 

 is essentially European in distribution ; B. Americana, on the 

 contrary, American. 



Yar. GOULDII, Yerrill. PL 29, fig. 68. 



Ribs sharper, more produced on the shoulder-angle, no spiral 

 lines on the shoulder, those on the middle of the body-whorl 

 fewer and more distant than in the typical form. 



Massachusetts to Nova Scotia. 

 B. IMPRESSA, Beck. PL 33, fig. 69. 



Shell wide, with short spire, and sloping but rather well- 

 defined shoulder ; densely costulate longitudinally, crossed by 

 about ten spiral riblets, forming a cancellated surface ; yellowish 

 ash-color. Length, 15 mill. 



Spitzbergen ; Nova Zembla. 



B. CONCINNULA, Yerrill. PL 29, fig. 54 ; PL 27, fig. 27. 



Shoulder sloping, the angle not acute ; ribs numerous, often 

 20 to 25, crossed by strong spiral lines, forming a nodulous 

 surface, including the shoulder; whitish under a pale greenish 

 epidermis. Length, 10-1T5 mill. 



New England to Nova Scotia. 



The sloping shoulder, less defined carination, tuberculated 



