482 
A . E. Verrill — Catalogue of Marine Mollusca. 
liela bicarinata (continued.) 
Variety, violacea (Mighels and Adams). 
Plewrotoma violacea Mighels and Adams, Proc. Boston Soc. Nat. Hist., i, p. 50, 1841 : 
Boston Journal Nat. Hist., iv. p. 51. pi. 4, fig. 21. 1842. 
Defrancia cylindruceu, D. Beckii and D. livida Moller. Ind. Moll. G-ronl.. K rover’s 
Tidss., iv, pp. 86, 87, 1842. 
Mangelia violacea Stimpson, Shells New Eng., p. 49, 1851. 
Bela violacea H. and A. Adams, Genera Recent Mollusca, i, p. 95, 1858. 
Gould, Rep. on Invert, of Mass.. Binney’s ed., p. 353, fig. 622. 
G. 0. Sars, Mollusca Reg. Arctic* Norvegiae, p. 238. pi. 17. figs. 2, 3; pi. ix, fig. 
8, (dentition), 1878. 
Plev/rotoma grcenlandica and P. rugulata Reeve, (t. Jeffreys). 
Plate LVII, figures 16, 16a. 
Shell rather small, ovate-fusiform, with a moderately high, taper- 
ing spire, varying considerably in the proportion of length to breadth. 
Whorls six or seven, rounded, slightly obtusely shouldered on the 
lower whorls, at some distance below the suture, but more decidedly 
carinate-shouldered on the upper ones; ribs rudimentary or absent. 
The subsutural band is well-marked, sloping regularly from the suture 
to the shoulder, and usually crossed by numerous more or less distinct 
riblets, which are strongly excurved, and coincident with the lines 
of growth ; on the upper whorls these riblets are more evident, a lit- 
tle prominent, and often cross the carina and extend below the shoul- 
der, but usually only to a small extent ; on the lower whorl the riblets, 
even on the subsutural band, are obsolete or cannot be distinguished 
from the lines of growth, which are tine and wavy. On the upper 
whorls, below the nuclear ones, there are usually two strong, raised, 
spiral cinguli, the upper one forming the carina of the shoulder ; the 
other is about midway between the shoulder and the suture ; between 
and below these are others that are finer, but of the same character, 
the total number, on the penultimate whorl, being usually seven or 
eight ; one of these occasionally becomes as large as the two carina; ; 
on the last whorls the cinguli become more uniform in size, and more 
numerous, so that usually only the carina at the shoulder is distin- 
guishable from the rest of the cinguli, and in var. violacea , even this 
is not always distinctly larger; on the subsutural band, there are 
tine, spiral lines, either just above the shoulder, or over the whole 
surface. The spiral cinguli are usually alternately larger and smaller, 
and are everywhere crossed by the lines of growth, which are some- 
times so strong as to produce a finely cancellated appearance, under 
a lens. On the lower whorls the cinguli are sometimes so close that 
they are only separated bv fine, impressed or incised spiral grooves. 
