262 
MARINE SHELLS OF WEST COAST OF NORTH AMERICA 
SECTION CERITHIOPSIDA Bartsch, 1911 
Cerithiopsis antemunda Bartsch, 1911 
Plate 68, fig. 4 
Proceedings of the United States National Museum , 40:359; PI. 36, fig. 4. 
Shell elongate-conic, brown. (Nuclear whorls decollated.) Post-nuclear 
whorls appressed at the summit, very slightly rounded, marked by three 
spiral cords, of which the first—which is at a little distance anterior to the 
summit—is obsolete on the first four whorls, giving them a decidedly 
shouldered appearance, while on the last turn it is almost equal to the 
other two. The second cord is a little posterior to the suture. The spaces 
between these spiral cords are about double the width of the spiral cords. 
In addition to the spiral sculpture, the whorls are marked by slender, 
well-rounded, retractive, axial ribs, equaling the spiral cords in strength. 
Of these ribs, 14 occur upon the first to fourth, 16 upon the fifth and sixth, 
and 20 upon the penultimate turn. The junctions of these axial ribs and 
spiral cords form well-rounded tubercles, while the spaces inclosed between 
them are strongly impressed, squarish pits. Sutures strongly channeled, 
showing the posterior edge of the peripheral cord. Periphery of the last 
whorl marked by a strong, spiral cord, which is separated from the supra- 
peripheral cord by a sulcus as wide as that which separates the suprape- 
ripheral from the median cord, and, like it, is crossed by the continuations 
of the axial ribs which extend to the posterior edge of the peripheral cord. 
Base concave, with a slender fasciole surrounding the insertion of the 
columella and marked axially with fine, incremental lines, which also 
extend over the entire surface of the spire. Aperture subquadrate, strongly 
channeled anteriorly; posterior angle decidedly obtuse; outer lip thin, 
showing the external sculpture within, rendered sinuous at the edge by 
the external sculpture; columella stout, twisted with the edge reflected; 
parietal wall covered with a thin callus. Length, of the eight remaining 
whorls, 5; diameter, 1.9 mm. (Bartsch.) 
Type in United States National Museum, No. 213313. Type locality, 
U.S. Bureau of Fisheries, Station 2932, off San Diego, California. 
Range. San Pedro to San Diego, California. 
Cerithiopsis diegensis Bartsch, 1911 
Plate 70, fig. 4 
Proceedings of the United States National Museum, 40:347; PI. 40, fig. 4. 
Shell small, broadly elongate-conic, chestnut brown. Nuclear whorls 
two and one-half; the first smooth; the next turn has about 20 slender 
axial threads; while the last whorl has about 32 axial threads and two 
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