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224 American Seashells
y^ inch in length, rather thin, but quite strong; surface glossy. 7 whorls.
Suture well-impressed. Whorls in spire and upper third of body whorl with
about 15 obliquely slanting, strong, rounded, axial ribs. Numerous spiral,
incised lines are strongest on the base of the body whorl. Lower columella
area with a small shield. Outer lip thickened within by about a dozen small
white teeth. Color pinkish gray with indistinct motthngs of orange-brown.
A common littoral to shallow-water species.
Figure 50. Small whelks of the Pacific coast, a, Amphissa versicolor Dall; b, A.
Columbiana Dall; c, A. undata Cpr.; d, Searlesia dira Reeve. All X3.
Amphissa columbiana Dall
Alaska to San Pedro, California.
Columbian Amphissa
Figure 50b
I inch in length, similar to versicolor, but characterized by its large size,
numerous, weak, vertical, axial ribs (20 to 24 on the next to the last whorl,
and missing on the last part of the last whorl), and by the low, rounded varix
behind the outer lip. Color yellow-brown with indistinct mauve mottlings.
Periostracum thin, yellowish brown. Moderately common in shallow water
from Oregon to Alaska.
Amphissa undata Carpenter Carpenter's Amphissa
Monterey, California, to Lower California.
Figure 50c
Vs to y2 inch in length, similar to versicolor, especially in color, but with