WEST AMERICAN PYRAMIDELLID MOLLUSKS. 23 



The specimen described and figured (Cat. no. 13522, U.S.N.M.) 

 comes from Guacamoyo, Mexico. It has eight post-nuclear whorls 

 and measures: Length 9.8 mm., diameter 3.5 mm. 



PYRAMIDELLA (LONGCH^US) MEXICANA, new species. 



Plate 1, fig. 12. 



Shell, large, robust, broadly conic, dull brown. (Nuclear whorls 

 decollated.) All but the last post-nuclear whorl flattened, flatly 

 shouldered and crenulated at the summit; the last inflated and 

 well rounded. Periphery of the last whorl marked by a strong 

 sulcus. Sutures chamieled. Entire surface of spire and base 

 marked by lines of growth, which are quite prominent (m the last 

 turn. Base inflated, strongly rounded, with a slender fasciole at 

 the insertion of the columella. Aperture oval; posterior angle 

 acute; slightly channeled anteriorly; outer lip thin, mth a white 

 band at the periphery, the remainder brown with darker colored 

 lines, reenforced deeply witliin by five spiral cords, two of which 

 are posterior and three anterior to the periphery; columella stout, 

 conic, with a strong lamellar fold at its insertion and two much 

 more obhque ones anterior to it. 



The type (Cat. no. 105558, U.S.N.M.) comes from Scammon La- 

 goon, Lower California. It has lost the nucleus and probably the 

 first post-nuclear turn; the tliirteen remaining measure: Length 19 

 mm., diameter 6.5 mm. Another specimen (Cat. no. 56764, U.S.N.M.) 

 was collected at San Diego, California. 



PYRAMIDELLA (LONGCH.,EUS) CONICA C. B. Adams. 

 Plate 1, fig. 9. 

 PyramideUa conica C. B. Adams, Ann. Lye. Nat. Hist, of N. Y., 1852, p. 424. 



Shell very regularly elongate, conic. Early whorls flesh-colored; 

 later ones light brown with an occasional varix of flesh color. Nu- 

 clear whorls at least two and one-half, depressed hehcoid, having 

 their axis almost at right angles to that of the succeeding turns, in 

 the first of wliich they are about half immersed. Post-nuclear 

 whorls decidedly flattened, sfightly shouldered and weakly crenu- 

 lated at the summit, marked with a strong peripheral sulcus which 

 is crossed by numerous axial threads. Periphery' of the last whorl 

 slightly angulated. Base short, well rounded, provided with a 

 strong fasciole at the insertion of the columella. Entire surface 

 of spire and base marked by numerous exceedingly fine lines of 

 growth only. Aperture? Posterior angle acute; outer hp fractured, 

 reenforced within by five slender lirations. Columella strong, 

 slightly revolute. Posterior lamella very strong; anterior two much 

 weaker and much more obhque. Parietal wall glazed with a faint 

 callus. 



