86 
MARINE SHELLS OF WEST COAST OF NORTH AMERICA 
Post-nuclear whorls flattened; moderately shouldered at the summit, which 
is crenulated. Periphery with a strong sulcus. Base moderately long, 
well-rounded. Entire surface of spire and base marked by fine lines of 
growth and exceedingly fine, microscopic spiral striations. Aperture 
oval; outer lip thin, showing the following color markings within; a 
white zone at the periphery, a narrow chestnut band immediately pos¬ 
terior to the periphery and another at the summit, a broad band extending 
over half the base immediately below the peripheral zone; deep within, the 
lip is re-enforced by five strong, spiral cords, one at the periphery, two 
on the base, and two between the periphery and the summit; columella 
strong, provided with a strong fasciole, posterior fold very strong, 
lamellar, anterior two very oblique, slender. Length, 11.3; diameter, 
3.8 mm. (Bartsch.) 
Type in United States National Museum. Type locality, Cape San 
Lucas, Lower California. 
Range. Monterey, California, to Mazatlan, Mexico. 
Figured specimen No. 11866, in United States National Museum 
comes from La Paz, Lower California. 
Pyramidella mazatlanica Dali and Bartsch, 1909 
Bulletin 68, United States National Museum, 24; PI. 1, figs. 7, 7a. 
Shell very regularly conic, horn color, with a darker band on the 
middle between the sutures, which is bordered at its anterior margin 
by a faint light line. Nuclear whorls two, 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 two-thirds immersed. Post-nuclear whorls 
flattened, scarcely at all contracted at the suture, with a narrow, very finely 
crenulated shoulder at the summit. Sutures well-impressed. Periph¬ 
ery of the last whorl strongly, sharply, and deeply sulcate. Base short, 
well-rounded, with a strong fasciole at the insertion of the columella. 
Entire surface of the spire and base marked only by lines of growth. 
Aperture irregularly oval; posterior angle acute, with a moderate channel 
anteriorly; outer lip thin, re-enforced by four strong internal lirations, 
two of which are above and two below the periphery; columella slender, 
twisted and revolute, posterior fold lamellar, anterior two slender and 
very oblique. Length, 11; diameter, 3.5 mm. (Dali and Bartsch.) 
Type in United States National Museum, No. 162714. Type locality, 
United States Bureau of Fisheries Station 3019, in 14 fathoms, off Cape 
Tepoca, west coast of Mexico. 
Range. San Diego, California, to Cape Tepoca, west Mexico. 
