124 
MARINE SHELLS OF WEST COAST OF NORTH AMERICA 
seven equal parts. Sutures well-impressed. Periphery of the last whorl 
angulated. Base short, marked by eight strongly incised spiral lines, 
which decrease in spacing from the periphery to the umbilical area. The 
space immediately behind the columella bears a number of closely spaced, 
fine, spiral striations. Aperture rhomboidal; posterior angle obtuse; outer 
lip thin, showing the external markings within; columella slender, some¬ 
what twisted, and slightly revolute. Length, 6.2; diameter, 2.1 mm. 
(Dali and Bartsch.) 
Type in United States National Museum, No. 160200. Type locality, 
San Pedro, California. 
Range. San Pedro to San Diego, California. 
Turbonilla obesa Dali and Bartsch, 1909 
Plate 55, figs. 3, 3 a 
Bulletin 68, United States National Museum, 78; PI. 7, figs. 3, 3a. 
Shell robust, chocolate-brown. Nuclear whorls small, deeply obliquely 
immersed in the first post-nuclear turn, above which only the tilted edge 
of the last one projects. Post-nuclear whorls flattened, moderately shoul¬ 
dered at the summit, marked by strong vertical axial ribs, which are 
decidedly contracted at their junctions with the spiral grooves, which 
lends them a somewhat nodulous aspect. Of these ribs, sixteen appear 
on the first, eighteen upon the second, twenty upon the third to fifth, 
twenty-two upon the sixth, and twenty-four upon the penultimate turn. 
Intercostal spaces about as broad as the ribs, crossed by five strongly 
incised spiral grooves which almost cross the ribs. One of these is at 
the periphery. The remaining four appear in a double series; the one 
placed about as far below the summit as the other is above the periphery, 
the space between them being wider than that between the summit and 
the first pit below it. Two fine incised spiral lines mark the space be¬ 
tween the summit and the first series of pits below it. Periphery of the 
last whorl marked by a broad plain band, well-rounded. Base very short, 
well-rounded, marked by about six unequal and unequally spaced strong 
incised lines. Aperture pear-shaped; posterior angle acute; outer lip thin, 
showing the external sculpture within; columella oblique, slightly revo¬ 
lute, provided with a moderately strong fold at its insertion. Length, 5.2; 
diameter, 1.8 mm. (Dali and Bartsch.) 
Type in United States National Museum, No. 162563. Type locality, 
Pacific Beach, California. 
Range. Known only from type locality. 
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