128 BULIMULUS-ORTHOTOMIUM. 



gruneri Pfr. (=Drymceus virgo Lea !) and B. artemisia Binn. noticed 

 by von Martens, are merely adventitious. 



B. NIGROMONTANUS Dall. 



Shell short, wide, white, with 5 whorls, rather rudely striated in 

 harmony with the lines of growth, nuclear whorls 2, neatly, evenly 

 sculptured with fine, usually wavy, minute ribs, the summit with a 

 small central funicular dimple; whorls moderately rounded, the 

 last much the largest, the spire obtusely conical ; base full and 

 rounded, with a rather large, deep and subcylindrical umbilicus ; 

 outer lip sharp, hardly reflected ; pillar lip reflected rather widely 

 near the body around (not over) the umbilicus ; body with a thin 

 wash of callus, the outer lip strongly incurved at its junction, giving 

 a somewhat tubular look to the suture ; substance of the shell thin, 

 without markings. Length 18, of the last whorl 13, maximum 

 diameter 11 mill. (Dall). 



Summit of Black Mountain, Sonora, Mexico (Dr. Mearns). 



Bulimulus (alternatus var. /) nigromontanus DALL, Proc. U. S. 

 Nat. Mus., xix, p. 357. 



The shells above described are not in the best condition, and I 

 have some hesitation in describing them, but after an exhaustive 

 comparison with the Bulimuli of the region and of Lower Califor- 

 nia I find none to which the present form can be confidently as- 

 signed. It recalls somewhat B. xantusi Binney, and B. baileyi 

 Dall, but is smaller and more globose than either. In form some of 

 the varieties of B. alternatus Say, come nearest to it, but have a 

 different surface and marking, which are absent from the present 

 form, and none of them has so deep and cylindrical an umbilicus. 

 I have thought it best, therefore, to put it on record until the recep- 

 tion of more material shall enable a final decision to be made. 

 (Dall). 



B. DEALBATUS (Say). PI. 17, fig. 1 ; pi. 18, figs. 27, 28, 29, 30, 48. 



Shell umbilicate, ovate-conic, thin; corneous brown streaks which 

 are slightly translucent alternating with opaque cream-white or 

 light brown ragged streaks, either tint sometimes predominating. 

 Sculpture of slight growth-wrinkles generally becoming stronger 

 and more regular on the spire, the uepionic If whorls typically 

 with subobsolete fine longitudinal riblets, almost smooth. Whorls 

 about 6J, convex. 



