CLASS GASTROPODA 
21 
intervening. Sutures channeled. Aperture irregular, channeled anteriorly; 
posterior angle obtuse; outer lip thin, sinuous, showing the external sculp¬ 
ture within; columella stout, short, twisted and reflected; parietal wall 
glazed with a moderately thick callus. Length, 7.8; diameter, 2.7 mm. 
(Dali and Bartsch.) 
Type in Dominion Geological Survey Collection. Type locality, 
Ucluelet, Barkley Sound, Vancouver Island, British Columbia. 
Range. Known only from type locality. 
Bittium attenuatum Carpenter, 1864 
Plate 78, figs. 1, 2, 5 
Supplementary Report, British Association for the Advancement of Science, 655. 
Proceedings of the United States National Museum, 40: 393; PI. 54, figs. 1, 2, 5. 
B. t. valde gracili, attenuata; anfr. nucl.(detritis) ; normalibus 10 
planatis, suturis baud impressis; t. juniore lirulis spiralibus 2 anticis con- 
spicuis, aliis posticis parum conspicuis, supra costulas circiter 11, radiantes 
transeuntibus; t. adulta costulis et lirulis anticis obsoletis; lirulis 2. sutu- 
ralibus; basi prolongata, striis circiter 6 ornata; apertura ovali; columella 
intorta, parum emarginata. Long., .4; long, spir., 31; lat., 11 poll. (Car¬ 
penter.) 
Shell elongate-conic, varying in color from plain white to brown, vari¬ 
ously banded or maculated. Nuclear whorls two, moderately rounded, 
smooth. Post-nuclear whorls slightly rounded, ornamented with weak 
spiral bands, which are best developed on the early whorls. These spiral 
bands are truncated anteriorly and slope gently to the posterior boundary. 
The early whorls have three spiral bands, of which the posterior, at the 
summit, is less strongly developed than the other two, which divide the 
remaining space between the sutures equally. On the middle whorls the 
posterior keel has a tendency to become divided, while on the later turns 
it becomes obsolete. In addition to the spiral sculpture, the whorls are 
marked by poorly developed, rounded, protractive, axial ribs which render 
their intersections with the spiral cords nodulose. Of these ribs 12 occur 
upon the third and 14 upon each of the remaining turns upon which ribs 
are discernible. The spaces inclosed between the ribs and spiral bands are 
shallow, impressed, rectangular pits. In addition to the axial ribs, the 
whorls are marked by numerous fine lines of growth. Periphery of the last 
whorl marked by a spiral band, which is separated from the first band 
above the periphery by a sulcus as wide as the sulci on the spire. Base 
short, well-rounded, marked by six spiral keels, of which the first below 
the periphery is much larger than the rest, which are subequal and sub- 
equally spaced. Aperture ovate, somewhat effuse anteriorly; posterior 
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