138 
MARINE SHELLS OF WEST COAST OF NORTH AMERICA 
between the sutures, the intercostal spaces on the posterior third being 
smooth. The anterior three of these five lines of pits are of equal 
strength and equally spaced; the posterior two are weaker and a little 
closer together than the rest, the second one being a little farther distant 
from the median than that is from its neighbor anterior to it. Periphery 
and the somewhat attenuated base of the last whorl well-rounded, marked 
by the feeble continuations of the axial ribs and by nine incised, spiral 
lines, which vary considerably in strength and spacing. The first two of 
these, below the five already described, are of about the same strength 
as those immediately above the suture; the remainder are not so wide and 
less regular. Aperture moderately long, ovate; posterior angle acute; 
outer lip thin; inner lip oblique, somewhat curved, and slightly revolute; 
parietal wall glazed with a thin callus. Length, 7.2; diameter, 2.2 mm. 
(Bartsch.) 
Type in United States National Museum, No. 211554. Type locality, 
San Diego Bay, California. 
Range. Known only from type locality. 
Turbonilla canfieldi Dali and Bartsch, 1907 
Plate 53, figs. 3, 3 a; Plate 66, figs. 4, 4 a 
Proceedings of the United States National Museum , 33:504; PI. 47, figs. 4, 4 a. 
Shell slender, elongate-conic, with the posterior half of the exposed 
portion of the whorls on the spire white and the anterior half chestnut- 
brown, base white. Nuclear whorls two and two-thirds, large, smooth, 
forming a depressed helicoid spire whose axis is at right angles to the 
axis of the succeeding turn; not immersed, and extending slightly beyond 
the outline of the spire on both sides. Post-nuclear whorls very slightly 
rounded, weakly roundly shouldered at the summit and very moderately 
contracted at the periphery, ornamented by the very strong, broad, low, 
rounded, almost vertical axial ribs of which there are twenty-two upon the 
first, twenty-four upon the antepenultimate, and twenty-eight upon the 
penultimate turn. These ribs extend prominently to the summit and 
crenulate the subchanneled sutures. Intercostal spaces narrow, not more 
than half the width of the ribs, crossed by nineteen incised spiral lines, 
which are of almost equal width and subequally spaced with the following 
exceptions: the seventh, eleventh, and the last three above the periphery 
are much wider, appearing as quadrangular pits in the intercostal spaces, 
the eleventh falling on about the middle of the exposed portion of the 
whorl on the spire, and the seventh about half-way between this and 
the summit. Periphery and base of the last whorl well-rounded, the latter 
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