102 
MARINE SHELLS OF WEST COAST OF NORTH AMERICA 
developed axial ribs, of which sixteen occur upon the first three whorls, 
eighteen upon the fourth and fifth, twenty upon the sixth and seventh, 
twenty-two upon the eighth and the penultimate turn. Intercostal spaces 
about one and one-half times as wide as the ribs, well-impressed, terminat¬ 
ing about one-tenth of the width of the space between the sutures, posterior 
to the basal suture as a plain band. Sutures strongly constricted. Pe¬ 
riphery of the last whorl well-rounded. Base short, well-rounded. Entire 
surface of the spire and base marked by numerous microscopic, closely 
crowded, wavy, spiral striations. Aperture subquadrate, very broad at 
base, posterior angle obtuse; outer lip thin, bent very strongly at its basal 
angle; columella slender, slightly oblique, almost straight, weakly revolute. 
Length, 6.3; diameter, 1.9 mm. (Dali and Bartsch.) 
Type in United States National Museum, No. 206856. Type locality, 
United States Bureau of Fisheries Station 4322, off La Jolla, California. 
Range. Off Catalina Island to San Diego, California, in 197 fathoms. 
Turbonilla serrae Dali and Bartsch, 1907 
Proceedings of the United States National Museum , 33:497; PI. 44, figs. 8, 8a. 
Shell slender, very elongate-conic, subdiaphanous to milk-white. 
Nuclear whorls decollated. Post-nuclear whorls very high between the 
sutures, moderately rounded, slightly contracted at the periphery and 
somewhat shouldered at the summit, rendering the sutures subchanneled. 
The whorls are marked by subequal and subequally spaced, rather broad, 
rounded, almost vertical axial ribs, which are a little wider than the 
intercostal spaces; the depressed portion of the latter terminating a little 
above the suture. In the type which has lost the nucleus and probably 
the first two post-nuclear turns, there are sixteen ribs on the third of 
the remaining whorls, twenty upon the eighth, twenty-two upon the 
eleventh, and twenty-four upon the next, the penultimate turn. On this 
whorl the axial ribs are less regular and less strongly developed, showing 
senile degeneration. Periphery of the last whorl well-rounded. Base 
short, well-rounded, marked by slender continuations of the axial ribs, 
which extend feebly to the insertion of the columella. Entire surface of 
spire and base crossed by numerous, closely placed, spiral striations. 
Aperture subquadrate, posterior angle obtuse, outer lip thin, columella 
rather strong, somewhat oblique, and slightly revolute, without apparent 
fold in the aperture. Length, 7.7; diameter, 1.4 mm. (Dali and Bartsch.) 
Type in United States National Museum, No. 196198. Type locality, 
off Del Monte, Monterey, in 12 fathoms. 
Range. Known only from type locality. 
[400 ] 
