CLASS GASTROPODA 
97 
enforced immediately behind the edge by a strong varix, transparent, 
showing the external sculpture within; inner lip rather stout, decidedly 
curved, and strongly reflected over and appressed to the base; parietal wall 
covered with a thick callus which renders the peritreme complete. Length, 
2.2; diameter, 1.2 mm. (Bartsch.) 
Type in United States National Museum, No. 213698. Type locality, 
San Pedro, California. 
Range. San Pedro, California, to San Martin Island, Lower California. 
Alvania purpurea Dali, 1871 
Plate 82, fig. 1 
American Journal of Conchology, 7. Proceedings of the United States National Mu¬ 
seum, 41: PI. 31, fig. 1. 
Shell small, of four rounded whorls rather pointed. Sculpture of six 
or seven revolving ribs, on the last whorl, only two appearing on the second 
whorl; apical whorl smooth. These ribs are crossed by about twenty longi¬ 
tudinal riblets, which do not pass the second revolving rib on the last 
whorl. On the antepenultimate whorl they reach from suture to suture, 
and are conspicuously angulated at their intersection with the two revolv¬ 
ing ribs. Suture deep. Color whitish, the revolving ribs rounded, inter¬ 
rupted by the body whorl; peristome thickened, with a groove behind the 
columella. Altitude, .07; lat., .04 in. (Dali.) 
Type in United States National Museum. Type locality, Monterey, 
California. 
Range. Monterey, California, to San Martin Island, Lower California. 
Alvania aequisculpta Keep, 1887 
Plate 81, fig. 7 
West Coast Shells, 65: 1887. 
Shell very elongate-conic, light yellow. Nuclear whorls two, moder¬ 
ately well-rounded, marked by six spiral threads, which are about as wide 
as the spaces that separate them, and numerous slender, closely spaced, 
axial threads, which are about one-fourth as strong as the spiral threads 
between which they occur, giving the entire surface a finely reticulated 
appearance. Post-nuclear whorls appressed at the summit, with a sloping 
shoulder which extends over the posterior fourth between the sutures, 
marked by strong, slightly retractive, axial ribs which are about one-fourth 
as wide as the spaces that separate them. Of these ribs, 14 occur upon the 
first, 16 upon the second, and 18 upon the penultimate turn. In addition 
to the axial ribs, the whorls are marked between the sutures by three 
strong, spiral cords which are almost as strong as the ribs and divide the 
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