CLASS GASTROPODA 
91 
Turbonilla santarosana Dali and Bartsch, 1909 
Plate 49, figs. 7, 7a; Plate 56, fig. 7 
Bulletin 68, United States National Museum, 36; PI. 2, figs. 7, 7a. 
Shell small, delicate, subdiaphanous to milk-white. Nuclear whorls 
two and one-half, forming a moderately elevated helicoid spire, the axis 
of which is at right angles to that of the succeeding turns, in front of 
which it is very slightly immersed. Post-nuclear whorls well-rounded, 
slopingly shouldered near the summit, slightly constricted at the suture, 
marked by broad, low, rounded, axial ribs which become somewhat flat¬ 
tened at the summit. Of these sixteen occur upon the first to fourth, 
eighteen upon the fifth and sixth, while upon the penultimate they are 
very much enfeebled and ill-defined. Intercostal spaces narrow, shallow, 
the depressed area terminating a little posterior to the suture. Sutures 
constricted. Periphery and base of the last whorl somewhat inflated. 
Aperture moderately large, rhomboidal; posterior angle obtuse; outer 
lip thin, showing the external sculpture within; columella very thin 
and strongly curved. Length, 4.5 ; diameter, 1.4 mm. (Dali and Bartsch.) 
Type in United States National Museum, No. 163239. Type locality, 
United States Bureau of Fisheries Station 2902, in 53 fathoms, off Santa 
Rosa Island, California. 
Range. Santa Rosa Island to San Diego, California. 
Turbonilla engbergi Bartsch, 1920 
Journal of the Washington Academy of Sciences, 10. 
Shell small, elongate, conic, thin, semitransparent, bluish-white. 
Nuclear whorls decollated. Post-nuclear whorls moderately rounded, 
appressed at the summit, marked by broad, slightly protractively slanting 
axial ribs, which fourteen occur upon all of the remaining turns except 
the last, on which there are sixteen. These ribs are a little broader than 
the spaces that separate them, and they become slightly flattened and 
weaker toward the summit. The intercostal spaces are deeply depressed 
pits, which terminate somewhat posterior to the summit of the succeeding 
turn, leaving a broad, smooth band at the suture. Suture strongly con¬ 
stricted. Periphery of the last whorl well-rounded, not crossed by the 
strong axial ribs. Base short, well-rounded, marked by incremental lines 
only. Aperture subquadrate, posterior angle obtuse; outer lip thin; inner 
lip slightly sinuous, decidedly obliquely inserted, the inner edge having 
a decidedly protractive slant; parietal wall devoid of callus. Altitude, 
3.7; diameter, 1.1 mm. (Bartsch.) 
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