172 
MARINE SHELLS OF WEST COAST OF NORTH AMERICA 
spiral, calcareous, centrally slightly concave on the outer side. Diameter 
of shell, 1.8; alt., 1.0 mm. (Dali.) 
Type in ? Type locality, Cumshewa Inlet, British Columbia. 
Range. Amchitka Island, Aleutians, to Queen Charlotte Islands, Brit¬ 
ish Columbia. 
Molleria drusiana Dali, 1919 
Proceedings of the United States National Museum, 56:358. 
Shell minute, of two and a half rapidly enlarging whorls, whitish, 
covered with an olivaceous periostracum; suture distinct, rather deep; 
whorl section circular, surface smooth except for microscopic incremental 
lines; base convex with a rather wide umbilicus; aperture circular, simple, 
sharp-edged; operculum calcareous, multispiral, centrally depressed on the 
outer side. Height, 1; larger diameter, 1.5 mm. (Dali.) 
Type in United States National Museum, No. 31117. Type locality, 
Constantine Harbor, Amchitka Island, Aleutian. 
Range. Amchitka Island to Glacier Bay, Alaska. 
Family TROCHIDAE 
Genus NORRISIA Bayle, 1880 
Shell thick, conoidal, orbicular, covered by an epidermis, smooth; 
widely umbilicated, umbilicus surrounded by the callous extension of the 
columella; outer lip not thickened or sculptured. (Arnold.) 
Type. Norrisia norrisii Sowerby. 
Distribution. Monterey, California, to Cerros Island, Lower Cali¬ 
fornia. 
Described as Trochiscus norrisii Sowerby. 
Norrisia norrisii Sowerby, 1838 
Annals and Magazine of Natural History, new ser. 2:96; text fig., p. 97. Tryon and 
Pilsbry, Manual of Conchology, 11:276; PI. 61, fig. 30. 
In its general form it approaches very nearly to Rotella, but differs 
from that genus in having a rather large and deep open umbilicus. The 
shell is nearly smooth; its lines of growth are, however, distinct, but not 
prominent. Its outer coat is of chestnut-brown color, but the inside is of 
a brilliant pearly luster. The border of the outer lip is nearly black, that 
of the inner is green, and the inside of the umbilicus is nearly colorless. 
Width, 1.7; axis, 1.3 in. (Sowerby.) 
Type in British Museum. Type locality ? 
Range. California to Cerros Island, Lower California. 
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