CLASS GASTROPODA 
105 
last whorl well-rounded, marked by the feeble continuations of the axial 
ribs and numerous, exceedingly fine, closely spaced, spiral striations; the 
latter may also be seen on the spire. Aperture moderately large, sub¬ 
quadrate; posterior angle obtuse; outer lip thin, showing the external 
sculpture within, inner lip moderately long, almost straight, provided with 
a very feeble fold at its insertion. Length, 6.9; diameter, 1.5 mm. 
(Bartsch.) 
Type in United States National Museum, No. 211548. Type locality, 
San Diego, California. 
Range. Known only from type locality. 
Turbonilla aresta Dali and Bartsch, 1909 
Bulletin 68, United States National Museum, 54; PI. 4, figs. 5, 5a. 
Shell very slender, milk-white. Nuclear whorls small, tw r o and one- 
half, forming a moderately elevated, helicoid spire, which has its axis 
at right angles to that of the succeeding whorls, and is not at all im¬ 
mersed. Post-nuclear whorls moderately rounded, marked by sublamellar, 
protractive axial ribs, which extend undiminished to the summit of the 
whorls, rendering this crenulated. There are fourteen of these upon the 
first three whorls, sixteen upon the fourth to eighth, eighteen upon the 
ninth, twenty upon the tenth and eleventh, and twenty-one upon the penul¬ 
timate turn. Intercostal spaces about one and one-half times as wide on 
all but the last three whorls; on the latter they are about as wide as the 
ribs and terminate a little posterior to the suture. Sutures strongly 
marked. Periphery of the last whorl faintly angulated. Base short, 
well-rounded. Aperture moderately large, subquadrate, posterior angle 
obtuse. Outer lip thin, bent almost at right angles to the anterior lateral 
angle. Columella slender, slightly curved and slightly revolute. Length, 
6.4; diameter, 1.2 mm. (Dali and Bartsch.) 
Type in United States National Museum, No. 206858. Type locality, 
University of California Station, Catalina Island. 
Range. Santa Rosa Island to San Diego, California. 
Turbonilla barkleyensis Bartsch, 1917 
Plate 51, fig. 9 
Proceedings United States National Museum, 52:641; PL 42, fig. 8; PL 44, fig. 9. 
Shell large, slender, elongate-conic, bluish-white. Nuclear whorls 
small, a little more than two and a quarter, depressed, helicoid, having 
their axis at right angles to that of the succeeding turn, in the first of 
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