134 
MARINE SHELLS OF WEST COAST OF NORTH AMERICA 
middle of the whorls to the summit, between the sutures. A secondary 
of the same color extends from a little posterior to the periphery to the 
middle of the base. Nuclear whorls small, two and one-half, forming 
a depressed helicoid spire, the axis of which is at right angles to that 
of the succeeding turns, in the first of which they are very slightly 
immersed. Post-nuclear whorls flattened in the middle, slightly rounded 
at the summit and at the periphery, ornamented by well-rounded, strong, 
almost vertical, axial ribs, which become weakened toward the summit. 
These ribs are scarcely indicated on the first and second whorls; upon 
the third and fourth there are twenty, upon the remaining (excepting 
the penultimate whorl, which has twenty) there are eighteen. Intercostal 
spaces about double as wide as the ribs, marked by nine spiral series of 
pits, all of which pass strongly upon the sides of the ribs, but do not 
cross their summits. Of these pits the peripheral one and the three 
anterior to the one at the summit are stronger than the rest; the spacfe 
separated by the second and third below the summit is a little wider than 
the rest, and the pits biting in the ribs render these somewhat nodulous 
at this place. Sutures well-impressed. Periphery of the last whorl 
well-rounded. Base moderately long, well-rounded, marked by the con¬ 
tinuations of the axial ribs which extend feebly to the umbilical region, 
and about eight weakly incised spiral lines, those nearest the periphery 
being somewhat interrupted by the ribs. Aperture suboval; posterior 
angle acute; outer lip thin, showing the external markings within; colum¬ 
ella slender, slightly twisted, and very oblique. Length, 5.8; diameter, 
1.7 mm. (Dali and Bartsch.) 
Type in United States National Museum, No. 206869. Type locality, 
San Pedro, California. 
Range. San Pedro to San Diego, California. 
Turbonilla antestriata Dali and Bartsch, 1907 
Plate 54, figs. 4, 4 a 
Proceedings of the United States National Museum , 33:506; PI. 45, figs. 4, 4 a. 
Shell large and strong, light brown. Nuclear whorls two and one-half, 
small, smooth, forming a depressed rounded helicoid spire, which projects 
somewhat beyond the left side of the outline of the spire of the later 
whorls and has its axis at a right angle to the axis of these, being about 
one-fourth immersed in the first turn. Post-nuclear whorls slightly 
rounded, ornamented by low, rounded, narrow, vertical, axial ribs which 
become decidedly flattened and enfeebled near the summit of the turns; 
there are nine of these ribs on the second, twenty upon the fifth, and 
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