WEST AMERICAN PYRAMIDELLID MOLLUSKS. 105 



the latter marked by the continviations of the axial ribs and eight 

 equally spaced series of spiral pits, of which those nearest the umbili- 

 cus are a little less strongly developed than the rest. Aperture 

 moderately large, oval; posterior angle acute; outer lip thin, showing 

 the external sculpture within; columella slender, decidedly curved, 

 and somewhat twisted. 



The type (Cat. no. 162685, U.S.N.M.) was dredged at U. S. Bureau 

 of Fisheries station 2823, off La Paz, in 26^ fathoms. It has seven 

 post-nuclear whorls and measures: Length 3.7 mm., diameter 0.8 mm. 

 Another specimen (Cat. no. 206878, U.S.N.M.) was dredged at LT. S. 

 Bureau of Fisheries station 2826, off Ceralvo Island, Gulf of Califor- 

 nia, in 9^ fathoms. 



TURBONttLA (PYRGISCUS) LEPTA, new species. 

 Plate 10, figs. 7, 7a. 



Shell elongate-conic, ver}' slender, milk-white. Nuclear whorls 

 one and three-fourths, depressed, helicoid, having their axis at right 

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

 very slightly immersed. Post-nuclear whorls slightly rounded, 

 marked by well-developed, straight, rounded, strongly retractive 

 axial ribs, of which there are 20 upon the first, 18 upon the second 

 to sixth, and 20 upon the i)enultimate turn. Intercostal spaces about 

 as wide as the ribs, marked by eight equal and equally spaced incised 

 spiral lines. Sutures well impressed. Periphery and base of the last 

 whorl well rounded, marked by the continuations of the axial ribs 

 and five equal and equally spaced incised spiral lines. Aperture oval; 

 posterior angle acute; outer lip thin, showing the external sculpture 

 within; columella slender, curved, and slightly re volute. 



The type (Cat. no. 162584, U.S.N.M.) was dredged at U. S. Bureau 

 of Fisheries station 2823 in 26^ fathoms, off La Paz, Lower California. 

 It has eight post-nuclear whorls and measures: Length 2.7 mm., 

 diameter 0.7 mm. 



TURBONILLA (PYRGISCUS) HISTIAS, new species. 

 Plate 10, figs. 8, 8fl. 



Shell elongate-conic, slender, posterior half between the sutures, 

 light yellow; anterior half of base, chestnut. Nuclear whorls two, 

 forming a depressed, helicoid spire, the axis of which is at right 

 angles to that of the succeeding turns, upon the first of which it 

 rests. Post-nuclear whorls slightl}' overhanging, flattened in the 

 middle, very slightly shouldered at the summit, quite strongly con- 

 tracted at the suture, marked by strong, somewhat sinuous, narrow, 

 retractive axial ribs, of which 18 occur upon all but the penultimate 

 turn, which has 24. Intercostal spaces about two times as wide as 

 the ribs upon all but the last turn, upon which they are a little nar- 

 rower, marked by eight equal and equally spaced spiral series of pits 



