148 BULIMULUS-ORTHOTOMIUM. 



me the original series collected by Gabb, I do not hesitate to separ- 

 ate the form specifically from B. xantusi. Of the latter, among- 

 others, we have one of the original specimens collected by Xantus. 



Group of B. inscendens. 



B. XANTUSI (W. G. Binney). PI. 19, figs. 60, 61, 62 ; pi. 33, fig. 36. 



Shell very deeply rimate or umbilicate, oblong-conic, thin ; white 

 under a thin light brown cuticle ; surface lusterless, densely wrinkled 

 longitudinally, wrinkles cut into oblong granules by revolving in- 

 cised lines (fig. 62), the granulation coarse for the size of the shell. 

 Whorls 6, the apex very obtuse, nepionic shell vertically ribbed, 

 obtusely carinated above, with rather straightly sloping lateral mar- 

 gins ; the following whorls convex, the last deeply excavated in the 

 umbilical region. 



Aperture less than half the shell's length, ovate ; edge of lip a 

 trifle expanded ; columellar margin broadly dilated, columella 

 slightly concave, not folded. 



Alt. 20, diaru. 10*, alt. of aperture 10 mill. (type). 



Alt. 2T5, diam. 11, alt. of aperture 9'2 mill. 



Alt. 21, diam. 10'2, alt. of aperture 9 mill. 



Cape St. Lucas, Lower California (Xantus). 



Bulimus xantusi W. G. B., Proc. Acad. N. S. Phila., 1861, p. 331, 

 fig. PFR., Mai. Bi., 1864, p. 45; Monogr., vi, p. 111. Bulimulus 

 (Scutalus} xantusi BINN. & BLD., Land and Freshwater Sh. N. A., 

 i, p. 210, f. 362. CROSSE & FISCHER, Moll. Mex., p. 518, pi. 21, f. 

 10, lOa. B. xantusi COOPER, Proc. Cal. Acad. Sci. (2), iii, p. 213 

 (in part?) ; iv, p. 138, pi. 5, f. 13, pi. 6, f. 29. Bulimulus (Mesem- 

 brinus) xantusi DALL, Proc. U. S. Nat. Mus., xvi, 1893, p. 641, pi. 

 72, f. 4. Scutalus xantusi TRYON, Amer. Journ. Conch., iii, p. 173, 

 pi. 14, f. 11. 



Finely but intensely granular, resembling B. montezuma on a 

 reduced scale, but with the lip-edge barely expanded, not reflexed. 

 It is closely allied to B. gabbi, but differs in being decidedly less 

 conic, with smaller aperture, and with high, laterally flattened 

 nuclear whorls, bluntly angular above, instead of well rounded as in 

 gabbi. 



B. DIGUETI J. Mabille. 



Shell openly umbilicate, quite thin, solid, subopaque, hardly shin- 

 ing ; corneous-rufescent, sometimes paler, and marked with opaque 



