NO. 2193. WEST AMERICAN MARINE MOLLUSKS—BARTSCH. 657 



well-rounded, narrow, almost straight, slightly protraetive axial 

 ribs, of which 18 occur upon all the turns. Intercostal spaces about 

 2^ times as wide as the ribs, crossed by 9 incised spiral lines, of which 

 the third and ninth are equal, and fully doubly as wide as the sec- 

 ond, fourth, and eighth, which are also equal, the rest being well- 

 incised, slender striations. In spacing the first is about as far an- 

 terior to the summit as it is distant from the second, and the second 

 is an equal distance from the third; the third, fourth, eighth, and 

 ninth have about the same spacing, while the space between the 

 fourth and fifth and seventh and eighth is only about one-half as 

 wide, the combined spaces between the fifth and seventh are about 

 equal to one of the spaces of the last-mentioned group, the sixth 

 spiral giving a little wider spacing to the area between the fifth and 

 sixth than the sixth and seventh. Suture moderately constricted. 

 Periphery of the last whorl obtusely angulated. Base short, well 

 rounded, marked by the feeble continuations of the axial ribs, which 

 become evanescent on its middle, and nine very slender and almost 

 equall}^ spaced, incised lines. Aperture subquadrate. Posterior 

 angle obtuse (outer lip badly fractured) ; inner lip very thick and 

 provided with a strong oblique fold a little anterior to its insertion ; 

 parietal wall glazed with a thin callus. 



The type, an adolescent specimen, Cat. No. 268731, U.S.N.M., was 

 dredged by the U. S. Bureau of Fisheries steamer Albatross at sta- 

 tion 5678 off Redondo Point, Magdalena Bay, Lower California, in 

 ISi fathoms, on broken-sliell bottom. It has 7^ postnuclear whorls 

 and measures — length, 3.9 mm. ; diameter, 1.25 mm. Cat. No. 267743, 

 U.S.N.M., contains an adult specimen dredged in shallow water in 

 Santa Maria Bay, Lower California, which has lost the nucleus and 

 probably the first three postnuclear turns, the 7^ remaining meas- 

 ure — length, 5.3 mm.; diameter, 1.8 mm. 



TURBONILLA (PYRGISCUS) CORSOENSIS, new species. 



Plate 45. fig. 8. 



Shell elongate conic, pale yellowish brown. Nuclear whorls 2^, 

 well rounded, forming a very depressed helicoid spire, the axis of 

 which is at right angles to that of the succeeding turns in the first of 

 which it is about one-fourth immersed. Postnuclear whorls flattened 

 in the middle, slightly shouldered at the summit, marked by rather 

 low, narrow, well-rounded, slightly retractively slanting axial ribs, 

 of which 18 occur upon the first, 16 upon the second to fourth, and 18 

 upon the remaining turns. The ribs become slightly flattened and en- 

 feebled toward the summit. Intercostal spaces about 2^ times as wide 

 as' the ribs crossed by nine almost equally spaced incised spiral grooves, 

 the first of which is about as far anterior to the summit as that is 

 65008°— Proc.N.M. vol.52— 17 42 



