268 
MARINE SHELLS OF WEST COAST OF NORTH AMERICA 
rounding the columella at its insertion, while the former divides the space 
between it and the peripheral cord into equal areas. In addition to the 
above sculpture, the entire base and spire are marked by numerous slender, 
incremental lines. Aperture irregularly subquadrate, strongly channeled 
anteriorly; posterior angle obtuse; outer lip thin, rendered sinuous at the 
edge by the external sculpture, which is apparent in the aperture; columella 
short, stout, twisted, with the free edge reflected; parietal wall glazed with 
a thin callus. Length, 7.2; diameter, 1.2 mm. (Bartsch.) 
Type in United States National Museum, No. 195198. Type locality, 
Whites Point, San Pedro, California. 
Range. San Pedro, California, to South Coronado Island. 
Cerithiopsis onealensis Bartsch, 1921 
Proceedings of the Biological Society of Washington, 34:35. 
Shell elongate-conic, pale chestnut brown. Nuclear whorls decollated. 
Post-nuclear whorls moderately rounded, slightly overhanging, crossed by 
very strong, broad, rounded, slightly protractively slanting axial ribs, of 
which 16 occur upon the first four turns, 18 upon the fifth, and 26 upon 
the last. Intercostal spaces about half as wide as the ribs. In addition to 
the axial ribs the whorls are crossed by three strong spiral cords, of which 
the one at the summit is a little less strong than the other two. The junc¬ 
tion of the axial ribs and spiral cords forms very prominent tubercles. 
Those on the cord near the summit are well-rounded. Those on the median 
cord are truncated posteriorly, and almost truncated anteriorly, while those 
on the cord above the suture are abruptly truncated posteriorly and slope 
moderately gently anteriorly. On the last whorl, where the ribs are much 
more crowded, the tubercles have an oblong outline, and are about equal on 
all three cords, their long axis coinciding with the axis of the shell. The 
pits inclosed by the spiral cords and axial ribs are well-rounded on all the 
whorls. Suture strongly impressed. Periphery of the last whorl marked 
by a sulcus about as broad as that separating the median from the super- 
sutural cord on the spire. Base short, well-rounded, marked by feeble con¬ 
tinuation of the axial ribs, which lend it a roughened aspect, and a single 
slender spiral thread, which encircles the base at the insertion of the colu¬ 
mella. Aperture decidedly channeled anteriorly; posterior angle obtuse; 
outer lip thin, showing the external sculpture within, sinuous at the edge; 
inner lip sigmoid, reflected over and appressed to the columella. Length, 
5.1; diameter, 1.9 mm. (Bartsch.) 
Type in United States National Museum, No. 340827. Type locality, 
off O’Neal Island, Puget Sound. 
Range. Puget Sound. 
[ 566 ] 
