122 
MARINE SHELLS OF WEST COAST OF NORTH AMERICA 
flattened in the middle, rounded toward the summit; of which sixteen 
appear upon the first and second, eighteen upon the third to fifth, twenty 
upon the sixth, twenty-two upon the seventh and the penultimate turn. 
Intercostal spaces almost as wide as the ribs, shallow. Sutures well- 
impressed. Periphery and the rather short base of the last whorl some¬ 
what inflated and well-rounded. Entire surface of spire and base marked 
by well-incised, closely spaced, fine, spiral striations; aperture rather 
small, oval; posterior angle acute; outer lip thin, showing the external 
sculpture and coloration within; columella sigmoid, slender, and slightly 
revolute. Length, 7; diameter, 2.3 mm. (Dali and Bartsch.) 
Type in United States National Museum, No. 15275. Type locality, 
off San Pedro, California. 
Range. Victoria, British Columbia, to San Diego, California. 
Turbonilla macouni Dali and Bartsch, 1910 
Canada, Department of Mines, Geological Survey Branch, Memoir No. 14-N, 15; 
PI. 1, fig. 9. 
Shell large, very broadly elongate-conic, pale wax-yellow, with three 
chestnut bands. The first of these bands extends over the posterior fourth 
of the whorls between the sutures, and is less strongly colored than the 
other two, which are very pronounced, about half as wide as the first, 
and occupy the space immediately anterior and posterior to the periphery; 
the space which separates them being a little narrower than the band. 
Nuclear whorls small, almost two; depressed, helicoid, having their axis 
almost at right angles to that of the succeeding turns; scarcely at all 
immersed. Post-nuclear whorls flattened on the posterior two-thirds 
between the sutures, slightly rounded anteriorly; moderately shouldered 
at the summit; marked by strong, well-rounded, somewhat sinuous, 
almost vertical, axial ribs which are as wide as the spaces which separate 
them. Of these ribs, eighteen occur upon the second, twenty upon the 
third and fourth, eighteen upon the fifth to seventh, twenty upon the 
eighth and ninth, twenty-two upon the tenth and penultimate turn. Pe¬ 
riphery of the last well-rounded. Base of the last whorl moderately long, 
well-rounded, marked by the feeble continuations of the axial ribs. En¬ 
tire surface of spire and base marked by numerous, closely spaced, very 
fine, spiral striations. Aperture moderately large, broadly oval; posterior 
angle obtuse; outer lip thin, showing the external markings within; 
parietal wall glazed with a thin callus. Length, 9; diameter, 3 mm. 
(Dali and Bartsch.) 
Type in Geological Survey Museum, Ottawa. Type locality, Barkley 
Sound, Vancouver Island, British Columbia. 
Range. Known only from type locality. 
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