WEST AMERICAN PYRAMIDELLID MOLLUSKS. 43 



The Amherst collection contains a tube with six specimens; one 

 of these is a splendid individual which undoubtedly served Professor 

 Adams for his diagnosis. We have used it for our description and 

 figure. It has twelve post-nuclear whorls, and measures: Length 

 5.5 mm., diameter 1.5 mm. They came from Panama. 



TURBONILLA (STRIOTURBONILLA) BUTTONI, new species. 

 Plate 3, figs. 4, 4a. 



Shell irregularly elongate-conic, yellowish-white. Nuclear whorls 

 two, very small, 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, ornamented by 

 very regular, rounded, somewhat sinuous, and decidedly protractive 

 axial ribs, which extend undiminished from the summit to the 

 periphery of the whorls and very feebly beyond this on the base. 

 There are 16 of these ribs upon the first to third, 18 upon the fourth 

 and fifth, 20 upon the sixth to ninth, and 22 upon the penultimate 

 turn. Intercostal spaces well impressed, about as wide as the ribs. 

 Sutures well marked, rendered wavy by the strong ribs. Peripher}^ 

 of the last whorl well rounded. Base short, well rounded. Entire 

 surface of spire and base marked by numerous exceedingly fine 

 wavy spiral striations. Aperture subquadrate, posterior angle 

 obtuse; outer lip thin; columella short, moderately strong, slightly 

 twisted and reflected, provided with a weak oblique fold at its inser- 

 tion. 



The type (Cat. no. 163241 U.S.N.M.) and nine specimens were 

 collected at San Pedro, California. It has eleven post-nuclear 

 whorls, and measures: Length 6.3 mm., diameter 1.5 mm. 



The following additional specimens have been examined: 



Named for Fred L. Button. 



