CLASS GASTROPODA 
143 
Periphery of the last whorl well-rounded. Base short, well-rounded, 
marked by the continuations of the axial ribs, which extend to the umbilical 
area, and 11 incised spiral lines, of which those immediately below the 
periphery are somewhat interrupted and wider than the rest. Aperture 
rhomboidal; posterior angle acute; columella rather stout, revolute. Length, 
8; diameter, 2.1 mm. (Dali and Bartsch.) 
Type in United States National Museum, No. 206870. Type locality, 
University of California Station 32, off Santa Catalina Island, California. 
Range. Known only from type locality. 
Turbonilla adusta Dali and Bartsch, 1909 
Bulletin 68, United States National Museum, 108; PI. 10, figs. 12, 12a. 
Shell robust, pale brown. (Nuclear whorls decollated.) Post-nuclear 
whorls flattened, slightly exserted at the summit, where they are moderately 
squarely shouldered, marked by well-developed, rounded, slightly retrac¬ 
tive, axial ribs, of which 20 occur upon the second and third, 22 upon 
fourth and fifth, 24 upon the sixth of the remaining turns, and 28 upon 
the penultimate whorl. Intercostal spaces equaling the ribs, crossed by a 
double series of spiral pits, five are strong and of equal strength, one of 
which is at the periphery, the other a little posterior to it, the third oc¬ 
cupies the middle of the space between the sutures, while the other two 
divide the space posterior to this into three equal areas. The fine lines are 
arranged in the following manner: between the second and third supra- 
peripheral pit, two fine lines; between the third and fourth, one; between 
the fourth and fifth, one; between the fifth and summit, two. Sutures 
well-impressed, rendered sinuous by the ribs. Periphery of the last whorl 
marked by a broad band, crossed by the extensions of the axial ribs, which 
continue feebly over the well-rounded base to the umbilical area. In addi¬ 
tion to these ribs, the base is marked by eleven incised spiral lines, the three 
immediately below the periphery being somewhat interrupted; the remain¬ 
ing are equal and equally spaced. Aperture ovate; posterior angle acute; 
columella slender, somewhat curved and reflected. Length, 5.7; diameter, 
1.7 mm. (Dali and Bartsch.) 
Type in United States National Museum, No. 206880. Type locality, 
San Diego, California. 
Range. Known only from type locality. 
Turbonilla castanella Dali, 1908 
Plate 53, fig. 7 
Bulletin 68, United States National Museum, 102; PI. 9, fig. 7. 
Shell very large, stout and heavy, chestnut-brown. Nuclear whorls 
decollated. Post-nuclear whorls well-rounded, ornamented by many broad, 
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