114 
MARINE SHELLS OF WEST COAST OF NORTH AMERICA 
Turbonilla tremperi Bartsch, 1917 
Plate 51, fig. 7 
Proceedings of the United States National Museum, 52:647; PI. 44, fig. 7. 
Shell short, elongate-conic, pale-brown. Nuclear whorls a little more 
than two, decidedly depressed helicoid, having their axis at right angles to 
that of the succeeding turns, in the first of which they are about one-fifth 
immersed. Post-nuclear whorls flattened in the middle, sloping toward the 
suture and the almost appressed summit, marked by strong lamellar, de¬ 
cidedly retractively slanting, axial ribs, of which 12 occur upon the first, 
14 upon the second to fourth, 16 upon the fifth, 18 upon the sixth, and 16 
upon the penultimate turn. These ribs extend prominently to the summit. 
Intercostal spaces strongly impressed, about 2j4 times as wide as the ribs. 
Suture moderately constricted. Periphery of the last whorl feebly angu- 
lated. Base short, well-rounded, marked by the very feeble continuations 
of the axial ribs, which become evanescent before reaching the umbilical 
chink. Entire surface of the shell marked with fine, closely spaced stria- 
tions. Aperture oval, posterior angle obtuse; outer lip thick; inner lip 
thick, almost straight, and slightly revolute; parietal wall covered by a 
thin callus. Length, 4.7; diameter, 1.2 mm. (Bartsch.) 
Type in United States National Museum, No. 250629. Type locality, 
outside San Diego Bay, California. 
Range. Known only from type locality. 
Turbonilla alaskana Dali and Bartsch, 1909 
Plate 52, fig. 9 
Bulletin 68, United States National Museum, 70; PI. 6, fig. 9. 
Shell elongate-conic, wax-yellow, with a broad, peripheral, light-brown 
band, and a narrow one immediately below the summit; these are best seen 
in the aperture. (Nuclear whorls decollated in all our specimens.) Post- 
nuclear whorls increasing very slowly in diameter in the first three turns, 
then more rapidly. The summits of succeeding turns fall a little below 
the periphery, which gives the whorls an overhanging appearance. The 
whorls are marked by very strong, well-elevated, broad, rounded, irregu¬ 
larly slanting, axial ribs, which become slightly widened and flattened both 
at the summit and at the periphery. There are about 18 of them upon all 
but the last turn; upon this there are about 22. Intercostal spaces about as 
wide as the axial ribs. Sutures strongly impressed. Periphery of the last 
whorl somewhat angulated, base moderately long, well-rounded, marked 
by feeble extensions of the axial ribs and many fine, closely spaced, wavy 
spiral striations; the latter also mark the spaces between the sutures. Aper¬ 
ture moderately large, ovate, posterior angle acute; outer lip moderately 
[412] 
