270 
MARINE SHELLS OF WEST COAST OF NORTH AMERICA 
incised lines. The intersection of these ridges and the ribs form the tu¬ 
bercles. The whorls slope gently from the second spiral ridge toward the 
summit and the first row of tubercles, which is only feebly developed and 
is located on the sloping shoulder. The second set of tubercles are rounded, 
while the third and fourth rows are decidedly elongated. Periphery of the 
last turn marked by a strong smooth spiral keel, which is separated from 
the supraperipheral keel by a mere constriction. Base rather short, without 
keel, marked only by lines of growth. Aperture suboval, decidedly chan¬ 
neled anteriorly; outer lip rendered sinuous by the external sculpture; 
columella short, very broad, and slightly expanded at the insertion, a little 
lighter in color than the rest of the shell; provided with a strong callus on 
its inner edge which is reflected over the parietal wall. Length, 4.2; diam¬ 
eter, 1.7 mm. (Bartsch.) 
Type in United States National Museum, No. 74001. Type locality, 
Monterey, California. 
Range. Known only from the type locality. 
Cerithiopsis truncata Dali, 1886 
Plate 70, fig. 2 
Proceedings of the United States Natiofial Museum, 9:304; PI. 4, fig. 5. 
Shell wax yellow. (Nucleus and early whorls decollated.) The four 
remaining, well-rounded, ornamented with three tuberculate spiral keels, 
of which the median is the strongest; the weakest is at the summit, which 
it crenulates. The last is midway between the suture and the median cord. 
In addition to the spiral cords, the whorls are marked by low, well-rounded, 
vertical, axial ribs, the intersection of which with the spiral cord renders 
them feebly tuberculate. Of these ribs, 30 occur upon the penultimate 
whorl and 22 upon the preceding turns. The spaces inclosed between the 
spiral cords and the axial ribs are squarish, well-impressed pits. A slender 
thread of the base is apparent in the somewhat constricted suture. 
Periphery of the last whorl marked by a sulcus which is about as wide as 
the spaces between the first and median cord and crossed by feeble con¬ 
tinuations of the axial ribs. Base short, well-rounded, with a slender 
fasciole at the insertion of the columella; entire surface of spire and base 
crossed by rather strong, incremental lines and numerous fine striations; 
aperture broadly ovate; decidedly channeled anteriorly; posterior angle 
obtuse; outer lip rendered wavy by the external sculpture; columella short, 
very broad, curved; parietal wall glazed with a thin callus which extends 
from the columella to the posterior angle. Length, 3.1; diameter, 1.9 mm. 
(Bartsch.) 
Type in United States National Museum, No. 213303. Type locality in 
the canals of sponges, at Unalaska. 
[ 568 ] 
