58 
MARINE SHELLS OF WEST COAST OF NORTH AMERICA 
Genus WILLIAMIA Monterosato, 1884 
Shell small, thin, apex recurved, and more or less acutely pointed, 
surface smooth, without sculpture. Siphonal groove is not visible from 
the outside, without emargination. The hooked recurved apex separates 
this genus from Siphonaria. (Oldroyd.) 
Distribution. California to Gulf of California. 
Williamia vernalis Dali, 1870 
Plate 2, figs. 19a, b 
American Journal of Concliology, 6:37; PI. 4, figs. 11 a-b. 
Shell small, thin conical; apex recurved, nearly in the median line, 
more or less acutely pointed; generally somewhat eroded in old specimens. 
Epidermis thin, not polished, smooth, brownish-red on the apex and in 
dead shells; in fresh or young individuals of a bright grass-green, some¬ 
what wrinkled and frequently overlapping the border of the shell; fuga¬ 
cious. Shell smooth, reddish-brown, with fifteen or more light yellow- 
green rays of color, radiating from the spire. There are no ribs or costae, 
but occasionally a moderately sharp line or two may be observed radiating 
from the apex, and impressed, as it were, from below. The apex is 
lighter than the rest of the shell. The interior is extremely polished and 
brilliant, and only in dead specimens is the mark of the siphon perceptible 
without a glass. The external colors are visible within the translucency of the 
shell. The siphonal groove is not visible from the outside, nor does it cause 
any extension or emargination of the edge of the shell. The aperture is 
roundly oval and the edge is simple. Long., .48; lat., .36; alt., .23 in. (Dali.) 
Type in United States National Museum. Type locality, Monterey, Calif. 
Range. Crescent City to San Nicolas Island and La Jolla, California. 
Williamia peltoides Carpenter, 1864 
Plate 2, fig. 17 
Annals and Magazine of Natural History, 13:474. Bulletin 112, United States Na¬ 
tional Museum; PI. 15, figs. 10 and 12. 
N. testa parva, laevi, cornea, subdiaphana, ancyliform, apice elevato 
valde inaequilaterali, strigis pallide castaneis radiata; intus nitidissima 
subaurantia. Long., .14; lat., .11; alt., .05 poll. (Carpenter.) 
Type in Liverpool Collection. Type locality, Cape San Lucas, Lower 
California. 
Range. Monterey to Catalina Island, to Gulf of California. This is 
the Nacella, Masatlan Catalogue, No. 263, page 203. 
Tablet 944 contains a solitary specimen of a Nacclla, of the shape and 
size of Ancylus fluviatilis, with the apex spirally recurved, and of a dark, 
horny color. It is not perfect enough for description. (Carpenter.) 
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