CLASS GASTROPODA 
151 
Shell broadly conic, wax-yellow at the tip, chestnut-brown on the last 
whorl, columellar area white. Nuclear whorls two and one-half, forming 
a depressed helicoid spire, whose axis is at right angles to that of the 
succeeding turns, in the first of which it is about one-fourth immersed. 
Post-nuclear whorls inflated, strongly rounded, moderately contracted at 
the suture, marked by very regular, rounded, strong, almost vertical axial 
ribs, of which eighteen occur upon the first, twenty-four upon the second, 
twenty-six upon the third, twenty-eight upon the fourth and fifth, thirty 
upon the sixth and seventh, and about forty upon the penultimate turn. 
Intercostal spaces a little wider than the ribs, crossed by five spiral series 
of broad, deep pits, which cause the five intermediate areas to appear as 
broad, raised bands, which are about as wide as the ribs, and render their 
junction with the ribs tuberculate. Sutures strongly impressed. Periphery 
of the last whorl well-rounded. Base moderately long, marked by the 
faint continuations of the axial ribs, and about ten spiral lirations, which 
are narrower and less strongly developed about the umbilical area. Aper¬ 
ture broadly oval; posterior angle acute; outer lip thin, showing the 
external markings within; columella strongly curved and completely re¬ 
enforced by the base. This specimen, described and figured No. 946b 
United States National Museum, came from San Pedro, California. 
(Bartsch.) 
Type locality, Santa Barbara, California. 
Range. San Pedro, California, to Point Abreojos, Lower California. 
Turbonilla arata Dali and Bartsch, 1909 
Bulletin 68, United States National Museum, 125; PI. 12, fig. 12. 
Shell large and rough. (Nuclear whorls decollated.) Post-nuclear 
whorls somewhat inflated and overhanging, appressed at the summit, well- 
rounded, with the greatest convexity on the anterior third between the 
sutures, marked by strong, narrow, rounded, well-raised, retractive, axial 
ribs, of which eighteen occur upon the first four, twenty upon the fifth, 
twenty-two upon the sixth and seventh, twenty-four upon the eighth, 
twenty-six upon the ninth, and twenty-eight upon the penultimate turn. 
Intercostal spaces about twice as wide as the ribs, marked by very deep pits, 
which leave the intervening spaces as strongly elevated cords, nine of 
which occur between the sutures. Of these cords, the second and fifth 
below the summit and the first above the periphery are of equal width and 
wider than the rest; the first, which forms the summit, and the three 
posterior to the one at the periphery, are again equal width; the third and 
fourth below the summit are a little more slender than the rest; the pit at 
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