CLASS GASTROPODA 
87 
Pyramidella mexicana Dali and Bartsch, 1909 
Bulletin 68, United States National Museum, 23; PI. 1, fig. 12. 
Shell large, robust, broadly conic, dull brown. (Nuclear whorls decol¬ 
lated.) All but the last post-nuclear whorl flattened, flatly shouldered 
and crenulated at the summit; the last inflated and well-rounded. Periph¬ 
ery of the last whorl marked by a strong sulcus. Sutures channeled. 
Entire surface of spire and base marked by lines of growth, which are 
quite prominent on the last turn. Base inflated, strongly rounded, with 
a slender fasciole at the insertion of the •columella. Aperture oval; pos¬ 
terior angle acute; slightly channeled anteriorly; outer lip thin, with 
a white band at the periphery, the remainder brown with darker colored 
lines, re-enforced deeply within by five spiral cords, two of which are 
posterior and three anterior to the periphery; columella stout, conic, with 
a strong lamellar fold at its insertion and two much more oblique ones 
anterior to it. Length, 19; diameter, 6.5 mm. (Dali and Bartsch.) 
Type in United States National Museum, No. 105558. Type locality, 
Scammons Lagoon, Lower California. 
Range. San Diego, California, to Scammons Lagoon, Lower Cali¬ 
fornia. 
Genus TURBONILLA Risso, 1826 1 
Shell with sinistral apex, cylindro-conic, many-whorled, generally 
slender; with a single columella fold which varies in strength and fre¬ 
quently is not visible in the aperture. The sculpture both axial and 
spiral ranges from obsolete to strongly incised lines or raised lamellae. 
(Bartsch.) 
Type. Turbonilla typica Dali and Bartsch. 
Distribution. World-wide; range from low water to 90 fathoms. 
Turbonilla gilli Dali and Bartsch, 1907 
Plate 49, fig. 8 
Proceedings of the United States National Museum, 33:493; PI. 44, fig. 5. 
Shell small, rather stout, inflated, dirty white. Nuclear whorls decol¬ 
lated, early post-nuclear whorls well-rounded, later ones flat, broader at 
the summit than at the suture; sculpture of about fourteen strong, 
almost vertical, scalariform axial ribs on the second, and sixteen quite 
protractive ones on the succeeding whorls; on the penultimate turn, 
however, they are less oblique than on those preceding it. These ribs 
are very strongly developed at the summit of the whorls and render the 
1 For descriptions of new species, received while this volume was in press, see 
Appendix, pp. 281-286. 
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