WEST AMEEICAN PYRAMIDELLID MOLLUSKS. 83 



TURBONILLA (PYRGISCUS; SIGNjE, new species. 



Plate 7, fig. L. 



Shell elongate-conic, of very regvilar outline, wax yellow, variegated 

 with ashy. (Nuclear whorls decollated.) Post-nuclear whorls very 

 flat, with appressed summits, scarcely at all contracted at the periph- 

 ery, marked by low, rounded, slightly sinuous, somewhat protractive 

 axial ribs, of which 22 occur upon the second, 24 upon the third, 26 

 upon the fourth, 28 upon the fifth, 30 upon the sixth, 36 upon the 

 seventh, 46 upon the eighth, and, of those remaining, the same num- 

 ber upon the penultimate turn. Intercostal spaces about half as 

 wide as the ribs, marked by six equal and equally spaced spiral rows 

 of pits, the last of wdiich is at a little greater distance from the summit 

 than its fellow. Sutures very faintly indicated. Periphery of the 

 last whorl somewhat angulated. Base short, well rounded, marked 

 by about a dozen fine, wavy, equal and equally spaced spiral lines. 

 Aperture rhomboidal; outer lip thick; columella moderately strong, 

 slightly sinuous and somewhat reflected. 



The type (Cat. no. 160210, U.S.N.M.) was collected by Mr. Roper 

 at San Pedro, California. It has lost the nucleus and probably the 

 first three post-nuclear whorls. The ten remaining measure: Length 

 10.2 mm., diameter 2.7 mm. 



TURBONaLA (PYRGISCUS) STRIOSA C. B. Adams. 



Plate 7, figs. 8, 8a. 



Chemnitzin striosn C. B. Adams, Ann. Lye. Nat. Hist, of N. Y., 1852, p. 393. 



Shell elongate-conic, wax yellow, nuclear whorls at least two, 

 forming a planorboid spire, the axis of which is at right angles to 

 that of the succeeding turns, in the first of which it is about one-third 

 immersed. Post-nuclear whorls moderateh^ rounded, feebly shoul- 

 dered at the summit, A-ery slightly contracted at the sutures, marked 

 by poorly developed axial ribs which are scarcely at all expressed 

 on the first two whorls, and become decidedly weakened and irregu- 

 lar on the last. Of these ribs there are 24 upon the third to fifth, 26 

 upon the sixth, and 28 on the seventh wdiorl. Intercostal spaces as 

 irregular as the ribs and usually a little wider, marked by six equally 

 strong, and equally spaced, incised spiral lines, which become quite 

 irregular on the last whorl. Sutures well impressed. Periphery 

 and base of the last w^horl well rounded, the latter marked by six 

 equally strong incised spiral lines. Aperture moderately large, oval; 

 outer lip thin, showing the external sculpture within; columella 

 slender, twisted and slightly revolute. 



Professor Adams's type, wdiich has served for our description and 

 figure, is in the Amherst College collection and comes from Panama. 

 It has nine post-nuclear whorls and measures: Length 5.4 mm., 

 diameter 1.5 mm. 



