CLASS GASTROPODA 
105 
Periphery and base of the last whorl well-rounded, the latter ornamented 
by spiral sculpture similar to that between the sutures, but a little more 
distantly spaced and more strongly impressed. Eighteen of the spiral lines 
appear between the sutures upon the penultimate whorl and ten upon the 
base. Aperture large, oblique, decidedly effuse anteriorly; posterior angle 
acute, peristome continuous; columella strong, short, somewhat twisted 
and slightly revolute. Long., 6.3; diameter, 2.5 mm. (Bartsch.) 
Type in United States National Museum, No. 168605. Type locality, 
Pacific Beach, California. 
Range. San Pedro, California, to Coronado Islands. 
Rissoina bakeri Bartsch, 1902 
Plate 83, fig. 4 
Nautilus, 16:9. Proceedings of the United States National Museum , 49:56; PI. 33, 
fig. 4. 
Shell small, sub-diaphanous to milky white. Nuclear whorls two, quite 
large, with beveled shoulder, smooth. Later whorls well-rounded, some¬ 
what angulated about one-fourth below the summit, ornamented by about 
twelve to fourteen quite well-developed axial ribs and a series of promi¬ 
nent axial striations, between them in the intercostal spaces, which are 
about four times as wide as the ribs; both ribs and striations extend from 
the summit of the whorls to the umbilical region, which is bordered by a 
basal fasciole. Sutures simple, well-marked. Aperture large, very oblique, 
sub-oval, slightly notched at the posterior angle. Outer lip varicose. Long., 
2.7; diameter, 1.0 mm. (Bartsch.) 
Type in United States National Museum, No. 130562. Type locality, 
San Pedro, California. 
Range. San Pedro to Coronado Islands. 
Rissoina cleo Bartsch, 1915 
Plate 83, fig. 3 
Proceedings of the United States National Museum, 49:58; PI. 33, fig. 3. 
Shell small, elongate-conic, milk-white. Nuclear whorls 2, well- 
rounded, slightly shouldered near the summit. Post-nuclear whorls well- 
rounded, very feebly shouldered at the summit, marked by slender, very 
distantly spaced, somewhat sinuous, decidedly protractive, axial ribs, of 
which 16 occur upon the first, 18 upon the second and third, and 20 upon 
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