NO. 1903. WEST AMERICAN PYRAMIDELLID M0LLU8K8—BARTSVH. 269 



wide as the first, and occupy the space immediately anterior and 

 posterior to the periphery, the space which separates them being a 

 Httle narrower than the band. Nuclear whorls small, almost 2; 

 depressed helicoid, having their axes almost at right angles to that of 

 the succeeding turns; scarcely at all immersed. Post-nuclear 

 whorls flattened on the posterior two-thirds between the sutures, 

 slightly rounded anteriorly; moderately shouldered at the summit; 

 marked by strong, well-rounded, somewhat sinuous, almost vertical, 

 axial ribs which are about as wide as the spaces which separate them. 

 Of these ribs, 18 occur upon the second, 20 upon the third and fourth, 

 18 upon the fifth to seventh, 20 upon the eighth and ninth, 22 upon 

 the tenth and penultimate turn. Periphery of the last whorl well 

 rounded. Base of the last whorl moderately long, well rounded, 

 marked by the feeble continuations of the axial ribs. Entire surface 

 of spire and base marked by numerous, closely spaced, very fine, 

 spiral striations. Aperture moderately large, broadly oval; posterior 

 angle obtuse; outer lip thin, showing the external markings within; 

 inner lip slender, moderately curved and slightly revolute; parietal 

 wall glazed with a thin callus. 



Specimens of this species were dredged in Barkley Sound, part of 

 which are in the Geological Survey Museum collection in Ottawa, 

 and two in the United States National Museum, where they are listed 

 as Cat. No. 211538, U.S.N.M. One of the specimens has the nucleus 

 and 10 post-nuclear whorls, and measures: Length, 9 mm.; diameter, 3 

 mm. Another has 10 post-nuclear whorls (having lost the nucleus and 

 probably the first 2 post-nuclear turns), and measures: Length, 14.8 

 mm.; diameter, 4.5 mm. 



In adult shells the basal band becomes much expanded, even to the 

 extent of covering the posterior half of the base. 



The present species — the finest of the west American Pyrgolam- 

 pros — recalls TurhoniUa (Pyrgolampros) Iceepi Dall and Bartsch, but 

 is much larger than that form, with fewer and stronger ribs. 



This species follows Turbonilla (Pyrgolampros) painei in the key. 



TURBONILLA (PYRGOLAMPROS) PESA Dall and Bartsch. 



Plate 35, fig. 5. 



Turbonilla (Pyrgolampros) pesa Dall and Bartsch, Dep. Mines, Geol. Surv., 

 Canada, 1910, p. 14, pi. 2, fig. 5. 



Shell, elongate-conic, small, chestnut brown, with a slightly paler, 

 broad, obscure band half way between the sutures. Nuclear whorls 

 decolated. Post-nuclear whorls flattened, slightly shouldered at 

 the summit, marked by feeble, almost vertical, axial ribs, of which 

 22 occur upon the second, 24 upon the third, 20 upon the fourth and 

 fifth, and 26 upon the sixth of the remaining turns. Upon the penult i- 

 mate turn the ribs are subobsolete. Intercostal spaces feebly 



