100 ODONTOSTOMUS. 



corneous-whitish: apex shortly conic, rather obtuse, suture scarcely 

 impressed, thread-like. Whorls 8, flattened, the first two nearly 

 smooth, the rest elegantly and densely striated; last whorl about two- 

 fifths the total length. Aperture vertical, ovate, nearly closed by 7 

 teeth, all remote from the margin. There are three thick lamelli- 

 form teeth : one angular, twisted and grooved parietal lamella, the 

 second tongue-shaped, on the columella, the third a twisted fold in 

 the middle of the right margin; within the basal lip there are 2-4 

 minute folds, and 2 minute ones within the upper part of the outer 

 lip; and there is a strong transverse lamella inward beyond the folds. 

 Peristome lipped, expanded, the margins joined by a thin callus, 

 the right margin subangular above. Length 26, diam. 11, length of 

 aperture 10^, width 8| mill. (Doering). 



Argentina: Sierra de la San Luis at S. Francisco. 



0. brackebuschii DOER., Apuntes Fauna Argent, iii, in Periodico 

 Zoologico ii, pt. 4, p. 240 (1877) Bulimus brackebuschii Doer., 

 KOBELT, Jahrb. 1878, p. 133; 1880, p. 288, pi. 9, f. 8-10. 



This species scarcely differs in the structure of the aperture from 

 0. dtzdaleus, especially the var. multidentatus, but it differs in its 

 cylindrical, not swollen form, blunter apex and flat whorls, which 

 show the young to be keeled. The basal impression is weaker than 

 in dcedaleus, and the minor denticles vary in the same way. It 

 differs from 0. multiplicatus Doer., in the wider, cylindrical shell, 

 with shortly conoid, not elongated apex; the flat whorls and scarcely 

 .impressed suture. It is narrower, thicker and more opaque than 0. 

 weyenberghi, and without a keeled suture. 



O. WEYENBERGHI Doering. PI. 14, figs. 13, 14. 



Shell rimate, subcylindrical, slightly ventricose, rather solid, 

 rufous-brown, not glossy; encircled above the suture with a whitish 

 carina. Spire somewhat club-shaped cylindrical, the apex shortly 

 conic, tapering, slightly obtuse, suture flat. Whorls 7, flattened, 

 the first nearly smooth, slightly convex, the rest delicately and 

 densely striate, the last whorl scarcely exceeding half the length 

 of the shell, encircled at the middle by a whitish band, sometimes 

 obsoletely carinate, the base compressed, scarcely pitted. Aperture 

 vertical, ovate, with 3 large and 4-7 smaller teeth : a large, sinuous 

 parietal lamella with three external cords, another very large tongue- 

 shaped and sinuous lamella on the columella, a third twisted and 



