24 BULLETIN 68, UNITED STATES NATIONAL MUSEUM. 



Prof. C. B. Adams's type, at Amiierst College, was collected at 

 Panama Bay. It has tliirteen post-nuclear whorls, and measures: 

 Length 13 mm., diameter 4.3 mm. 



The present species recalls P. (X.) mazatlanica, but differs in 

 being in every way much larger and having the sutures decidedly 

 more channeled. 



PYRAMIDELLA (LONGCH^US) MAZATLANICA, new species. 

 Plate 1, fig. 7, 7a. 



Shell very rcgidarly conic, horn color, with a little darker band 

 on the middle between the sutures, wliich is bordered at its anterior 

 margin by a faint hght Hne. Nuclear whorls two, forming a de- 

 pressed hehcoid spire, whose axis is at right angles to that of the 

 succeeding turns, in the first of which it is about two-tliirds im- 

 mersed. Post-nuclear whorls flattened, scarcely at all ccmtracted 

 at the suture, with a narrow, very finely crenulated shoulder at the 

 summit. Sutures well impressed. Periphery of the last whorl 

 strongly, sharply, and deeply sulcate. Base short, well rounded, 

 with a strong fasciole at the insertion of the columella. Entire sur- 

 face of spire and base marked only by hnes of growth. Aperture 

 irregularly oval; posterior angle acute, with a moderate channel 

 anteriorly; outer lip tliin, reenforced by four strong internal hrations, 

 two of wliich are above and two below the periphery; columella 

 slender, twisted and revolute, posterior fold lamellar, anterior two 

 slender and very oblique. 



The type (Cat. no. 162714, U.S.N.M.) was dredged at the U. S. 

 Bureau of Fisheries station 3019, in 14 fathoms, temperature 66°, 

 on broken shell bottom, off Cape Tepoca, west coast of Mexico. 

 It has thirteen post-nuclear whorls and measures: Length 11 mm., 

 diameter 3.5 mm. Another specimen (Cat. no. 46468, U.S.N.M.) 

 comes from tlie Gulf of Cahfornia. Two tips (Cat. no. 46477, 

 U.S.N.M.) come from San Diego. A fragment (Cat. no. 206855, 

 U.S.N.M.) was dredged by the U. S. Bureau of Fisheries station 

 3566 in 3 fathoms, off San Diego, California. 



SPECIES OK UNCERTAIN STANDtNO OF THE SUBGENUS LONOCH^US. 

 GDOSTOMIA LAMELLATA Carpenter. 

 Odostoniia laniellala Carpenter, Cat. Mazatlan Shells, 1856, p. 411. 



Tablet 1954, British Museum, contains Carpenter's cotypes. One 

 of these served for the description of the nucleus, and there is little 

 more to it. The other is a badly fractured specimen which has lost 

 the early whorls, the lip is broken so as to almost obliterate the 

 two weak basal folds of tlie columella. 



It maybe a young specimen of Pyrarnidella (Longchseus) mazatlanica. 



