NO. 2193. WEST AMERICAN MARINE M0LLU8KS—BART8CH. 6G1 



Base moderately long, well rounded, marked by the fine axial incre- 

 mental threads, and closely spaced, fine, Avavy, spiral striations. Aper- 

 ture broadly oval, somewhat effuse anteriorly ; posterior angle acute ; 

 outer lip thin showing the external sculpture within and rendered 

 sinuous at the edge by the strong markings; inner lip very slender, 

 strongly curved, reflected over, and appressed to the base for half its 

 length ; parietal wall covered by a thin callus. 



The type, and 42 specimens, Cat. No. 267740, were dredged in shal- 

 low water in Santa Maria Bay, Lower California. The type has 8^ 

 postnuclear whorls and measures — length, 5.7 mm.; diameter, 1.5 

 mm. Cat. No. 266536 U.S.N.M. contains another specimen dredged 

 in shallow water in Magdalena Bay, Lower California, and Cat. 

 No. 268640 U.S.N.M. contains three dredged by the U. S. Bureau of 

 Fisheries steamer Alhafross at station 5678, off Redondo Point, 

 Magdalena Bay, Lower California, in 13| fathoms on broken shell 

 bottom. 



TURBONILLA (MORMULA) SEBASTIANI. new species. 



Plate 42, fig. 9. 



Shell large, elongate-conic, pale brown. Nuclear whorls 2|, de- 

 cidedly depressed helicoid, having their axis at right angles to that 

 of the succeeding turns, in the first of which the tilted edge is about 

 one- fourth immersed. Postnuclear whorls well rounded, almost ap- 

 pressed at the summit, crossed by well-rounded, sublamellar, slightly 

 l^rotractively slanting axial ribs, of which 18 occur upon the first, 

 16 upon the second to seventh, 18 upon the eighth to tenth, and 20 

 upon the remaining turns. In addition to the axial ribs the whorls 

 are marked at irregular intervals by rather ill-defined varices. 

 Intercostal spaces about three times as wide as the ribs crossed by 

 14 incised spiral lines, of which the fourth, sixth, and fourteenth are 

 equal and much stronger than the rest. These are followed by the 

 second, eighth, eleventh, and thirteenth, which are also of equal 

 width but only about half as wide. The rest are also subequal and 

 about half as strong as the last named series. Suture moderately con- 

 stricted. Periphery obscurely angulated. Base short, well-rounded, 

 marked only by incremental lines and eight strong, incised, spiral 

 lines which decrease successively in spacing from the periphery ante- 

 riorly. Aperture small, subquadrate; posterior angle obtuse; outer 

 lip very thick, reenforced within by three spiral lamellae of which 

 the posterior two are very strong while the anterior one is feeble. 

 The median fold is about opposite the periphery of the last whorl, 

 while the posterior divides the space between this and the posterior 

 angle of the aperture in two equal parts. The anterior is a trifle 

 farther from the median than that is from the posterior fold. Inner 



