WEST AMERICAN PYRAMIDELLID MOLLUSKS. 127 



whorls are marked by stron<^, axial ribs, of which 16 occur upon the 

 second to fourth, 18 upon the fifth, and 20 upon the penultimate 

 turn. Intercostal spaces about twice as wide as the ribs, marked by 

 eleven incised spiral lines between the shoulder and the suture, which 

 are a little less strongly developed and a little closer spaced near the 

 suture. The shoulder is marked bj^ five slender, spiral lines. Periph- 

 ery and base of the last whorl well rounded, the latter marked by 

 the feeble continuations of the axial ribs, and about eighteen slender, 

 incised spiral lines. Aperture broadly oval; posterior angle acute; 

 outer lip rather thick; columella decidedly curved and somewhat 

 twisted. 



The t}T)e (Cat. no. 58334, U.S.N.M.) comes from the Gulf of Cali- 

 fornia. It has lost the nucleus. The seven remaining whorls meas- 

 ure: Length 5.6 mm., diameter 1.8 mm. 



TURBONILLA (PYRGISCULUS) CANCELLATA Carpenter. 

 Plate 12, fig. 6. 

 Dunheria cancellata Carpenter, Cat. Mazatlan Shells, 1856, p. 435. 



Shell reddish-brown. Nuclear whorls two, tumid, helicoid, having 

 their axis at right angles to that of the succeeding turns. Post- 

 nuclear whorls two and one-half, decidedly inflated, strongly angu- 

 lated at the summit ; marked by many acute axial ribs and somewhat 

 less strong spiral threads, which render the whorls elegantly can- 

 cellated. Outer lip angulated, columella without fold. 



Doctor Carpenter's tj'pe was foimd on a specimen of Spondylus at 

 Mazatlan, Mexico. It is preserved in the Liverpool collection on tab- 

 let 2009 in the British Museum. Tliis young individual has two and 

 one-half post-nuclear whorls, measuring: Length 0.95 mm., diameter 

 0.5 mm. It has very strong tabulated shoulders, acute lamellar 

 axial ribs, of which about eighteen occur on the last whorl, and fine, 

 spiral striations in the broad intercostal spaces. 



TURBONILLA (PYRGISCULUS) FESTIVA De Folin. 

 Plate 12, fig. 5. 

 Turbonilla /estiva De Folin, Les Meleagrinicoles, 1867, pp. 49, 50, pi. 5, figs. 4-6. 



Shell smooth, vitreous, elongate-conic. Nuclear whorls two and 

 one-half, forming a moderately elevated, helicoid spire, whose axis is 

 at right angles to that of the succeecUng turns, in the first of which 

 it is about one-fifth immersed. Post-nuclear whorls moderately 

 rounded, strongly contracted at the sutures, having a strong sloping 

 shoulder which extends over the posterior fourth of the space between 

 the sutures; the whorls are crossed by strong lamellose axial ribs 

 which extend over the periphery to the umbilical area. Ten of these 

 occur upon the first, 12 upon the second, and 8 upon the remaining 



