92 
MARINE SHELLS OF WEST COAST OF NORTH AMERICA 
Type in United States National Museum, No. 334489. Type locality, 
San Juan Island, Washington. 
Range. Known only from type locality. 
Turbonilla gabbiana Cooper, 1870 
American Journal of Conchology, 6:66. Bulletin 68, United States National Museum, 
35. 
Shell small, very slender, long, white; vertex broken; whorls eleven 
or more, flattened on the sides; sutures strongly impressed, ribs about 
twenty-three, large, obtuse, running from the suture to the margin of 
the base; base convexly truncated, smooth; aperture subcircular; colu¬ 
mella thick. Length, 10; diameter, 3.3 mm. (Gabb.) 
This shell can be readily distinguished by its extremely slender form 
and the strong, slightly oblique ribs. (Gabb.) 
Type in California Geological Survey. Type locality, Monterey, 
California. 
Range. Known only from type locality. 
Turbonilla muricatoides Dali and Bartsch, 1907 
Plate 49, figs. 11, 11a 
Proceedings of the United States National Museum, 33:495; PI. 14, fig. 2. Bulletin 68, 
United States National Museum, 38; PI. 2, figs. 11, 11a. 
Shell small, slender, subdiaphanous to milk-white; nuclear whorls 
two and one-half, helicoid but slightly elevated, well-rounded, having 
their axis at right angles to the axis of the post-nuclear turn. Post- 
nuclear whorls smooth, rather high between the sutures, moderately 
rounded, marked by strong sublamellar axial ribs, which are about half 
as wide as the spaces that separate them, and extend strongly to the 
very summit of the whorl where they render the well-marked sutures 
crenulate. There are fourteen of these ribs upon the first, eighteen upon 
the fifth, and twenty upon the penultimate turn. The depressed inter¬ 
costal spaces terminate abruptly at the periphery. Base of the last whorl 
well-rounded, smooth, without sculpture. Aperture: (outer lip frac¬ 
tured), columella slender, slightly twisted. Length, 3; diameter, 1 mm. 
(Dali and Bartsch.) 
Type in United States National Museum, No. 195942. Type locality, 
Monterey, California. 
Range. Known only from type locality. 
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