220 BELA. 
ribs, usually lower spire, finer spiral sculpture, etc. Towards its 
northern limit it becomes rather rare, according to Prof. Verrill. 
Sars’ figure of B. harpularia appears to represent a variety of 
B. turricula. 
B. AMERICANA, Packard. PI. 33, fig. 64; Pl. 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. 
Var. Goutnil, Verrill. 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. PI. 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-ecolor. Length, 15 mill. 
Spitzbergen; Nova Zembla. 
B. CONCINNULA, Verrill. PI. 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—11°5 mill. 
New England to Nova Scotia. 
The sloping shoulder, less defined carination, tuberculated 
