WEST AMERICAN PYRAMIDELLID MOLLUSKS. 109 



rounded, slightly retractive, axial ribs, of which 20 occur upon the 

 second and third, 22 upon the fourth and fifth, 24 upon the sixth of 

 the remaining turns, and 28 upon the penultimate whorl. Inter- 

 costal spaces equaling the ribs, crossed by a double series of spiral 

 pits, five are strong and of equal strength, one of which is at the 

 periphery, the other a little posterior to it, the third occupies the 

 middle of the space between the sutures, while the other two divide 

 the space posterior to this into three equal areas. The fine lines are 

 arranged in the following manner: Between the second and third 

 supra-peripheral pit, two fine lines; between the third and fourth, one; 

 between the fourth and fifth, one; between the fifth and summit, two. 

 vSutures w^ell impressed, rendered sinuous by the ribs. Periphery of 

 the last whorl marked by a broad band, crossed by the extensions of 

 the axial ribs, which continue feebly over the well-rounded base to the 

 umbilical area. In addition to these ribs, the base is marked by 

 eleven incised spiral lines, the three immediately below the periphery 

 being somewhat interrupted, the remaining are equal and equally 

 spaced. Aperture ovate; posterior angle acute; columella slender, 

 somewhat curved and reflected. 



The type (Cat. no. 206880, U.S.N.M.) was collected at San Diego, 

 California. It has lost the nucleus and probably the first post-nuclear 

 whorl. The eight remaining measure: Length 5.7 mm., diameter 

 1.7 mm. 



TURBONILLA (PYRGISCUS) LARUNDA, new species. 

 Plate 10, figs. 4, 4«, 4b. 



Shell elongate-conic, milk-white, with a broad yellow band a little 

 anterior to the middle of the whorls between the sutures. Nuclear 

 whorls two, forming a depressed helicoid spire, which has its axis 

 at right angles to that of the succeeding turns, upon the first of which 

 it rests, but is not immersed. Post-nuclear whorls flattened in the 

 middle, rounded at the summit, quite strongly contracted at the 

 suture, ornamented by narrow, sinuous, well developed, retractive 

 axial ribs, of which 16 occur upon the first to seventh, 18 upon the 

 eighth to ninth, and 20 upon the penultimate turn. Intercostal 

 spaces about three times as wide as the ribs, marked by eleven 

 incised spiral lines, of which the three immediately below the summit 

 and the one between the third and fourth above the periphery are 

 finer than the rest, and the fourth and fifth below the summit and 

 the peripheral one are of about equal width, and considerably stronger 

 than the intervening four, which are subequal. Periphery of the last 

 whorl well rounded. Base moderately long, well rounded, marked 

 by the continuations of the axial ribs and seven strongly incised sub- 

 equally spaced spiral lines, of which the three immediately below 

 the periphery are somewhat interrupted and stronger than the rest. 



