WEST AMERICAN PYRAMIDELLID MOLLUSKS. 65 



to that of the succeeding turns, in the first of which they are about 

 one-fourth immersed. Early post-nuclear whorls increasing but 

 little in diameter, rather high between the sutures, ornamented by 

 very slender, somewhat sinuous, almost vertical axial ribs. Later 

 whorls increasing more rapidly in diameter, less elevated between 

 the sutures, ornamented by low, broad, rounded, almost vertical 

 axial ribs, which become decidedly enfeebled as the}^ approach the 

 summit. There are almost 40 axial ribs upon the first, 34 upon the 

 second, 30 upon the third, 25 upon the fourth, 20 upon the fifth to 

 eleventh, and 22 upon the penultimate whorl. Intercostal spaces 

 mere lines, on the first whorl, on the later ones shallow impressed 

 areas of about half the width of the ribs. Sutures well marked. 

 Periphery of the last whorl inflated. Base short, well rounded, pos- 

 terior portion marked by the very feeble extensions of the axial ribs; 

 the anterior smooth, excepting the very fine and exceedingly closely 

 spaced spiral striations, which cover the entire surface of the shell. 

 Aperture subquadrate; posterior angle obtuse; outer lip thin, showing 

 the external sculpture within; columella slender, slightly twisted. 



The type and four additional specimens (Cat. no. 152751a, 

 U.S.N.M.), were collected by Mr. H. X. Lowe, in 10 fathoms off San 

 Pedro, California. The type has lost the nucleus. The ten remaining 

 whorls measure: Length 7.2 mm., diameter 2.2 mm. Cat. no. 

 204941, U.S.N.M., was dredged by Mrs. Oldroyd, in 4 fathoms off 

 San Pedro. Cat. no. 159982, U.S.N.M., one specimen from San 

 Pedro. Cat. no. 163257, U.S.N.M., San Pedro, collected by Mrs. 

 Oldroyd. Cat. no. 205948, U.S.N.M., one specimen from Pacific 

 Beach, collected by Mr. Henry Hemphill. One (Cat. no. 206864) 

 dredged at V. S. Bureau of Fisheries, station 4345, in 25 fathoms, 

 gray sand bottom, off Point Loma, California. 



TURBONILLA (PYRGOLAMPROS) HALIBRECTA, new species. 



Plate 5, figs. 10, 10a. 



Shell elongate-conic. Nuclear whorls two, depressed, helicoid, hav- 

 ing their axis at nearly right angles to that of the succeeding turns, 

 in the first of wdiich they are very slightly immersed. Post-nuclear 

 whorls flattened in the middle, slightly rounded toward the somewhat 

 shouldered summit and the periphery, marked by strong, rounded, 

 almost vertical axial ribs, of which there are 20 on the first to fifth, 

 18 upon the sixth, and 16 upon the remaining turns. Intercostal 

 spaces a little wider than the ribs, well impressed, sutures strongly 

 marked. Periphery of the last whorl well rounded, marked by the 

 feeble continuations of the axial ribs. Base short, well rounded. 

 Entire surface of spire and base marked by exceedingly fine, closely 

 crowTled, spiral striations. Aperture rather small, oval; posterior 

 angle acute; columella short and curved. 



