252 
MARINE SHELLS OF WEST COAST OF NORTH AMERICA 
Family CERITHIOPSIDAE 
Genus CERITHIOPSIS Forbes and Hanley, 1849 
Shell more or less cylindrical and slender, closely tuberculate or beaded, 
never varicose, nor umbilicate; spire tapering to an abrupt but elongated 
point; whorls numerous, the earliest very slender in proportion to the 
rest; suture narrow, excavated; mouth small; canal extremely short, trun¬ 
cated, and straight; operculum horny, ear-shaped, having an incomplete 
spire; nucleus nearly terminal, at the inner base of the mouth. (Jeffreys, 
British Conchology .) 
Type. Cerithiopsis tubercularis Montagu. 
Distribution. Europe, Pacific Coast of North and South America. 
SECTION CERITHIOPSIS, s.s. 
Cerithiopsis oxys Bartsch, 1911 
Plate 68, fig. 2 
Proceedings of the United States National Museum, 40:332; PI. 36, fig. 2. 
Shell minute elongate-conic, dark brown. Nuclear whorls almost four, 
forming a slender, elongate-conic spire, having the whorls well rounded. 
Post-nuclear whorls, well-rounded, separated by a strongly channeled 
suture marked by three equally strong, spiral cords, the first of which is 
at the summit, the third slightly above the periphery, while the second is 
median between these two. In addition to the spiral cords, the whorls 
are marked by vertical, axial ribs, almost as strong as the spiral cords. Of 
these ribs, 16 occur upon the first, 20 upon the second, 18 upon the third 
to fifth, and 24 upon the penultimate turn. The junctions of the axial ribs 
and spiral cords form strong tubercles of which those of the posterior 
cord are rounded while the other two are truncated posteriorly and slope 
gently anteriorly, while the spaces inclosed between the spiral cords and 
axial ribs are strongly impressed, rounded pits. Periphery of the last 
whorl marked by a strong cord which is feebly nodulose and separated 
from the tuberculate keel posterior to it by a channel as wide as those 
occurring on the spire; this channel is marked by the continuations of the 
axial ribs. Base moderately long, marked by a strong, spiral cord about 
halfway between the peripheral cord and the insertion of the columella, 
the spaces which separate it from the peripheral cord on one side and 
from the columella on the other, appearing as deep, rounded channels. 
Aperture rather small, irregularly ovate, very strongly channeled an¬ 
teriorly ; posterior angle obtuse; outer lip rendered sinuous by the external 
sculpture; columella very stout, twisted revolute, and reflected; parietal 
wall glazed with a thin callus. Length, 3.3; diameter, 1.2 mm. (Bartsch.) 
[ 550 ] 
