136 BULIMULUS-BOSTRYX-GEOCERAS. 



Aperture small, oblique, irregularly oval, the outer lip regularly 

 arcuate, simple; columellar lip /vf/r.ivW, <l//<itt<! ,///?/ r/^/vxxrf/ uhove. 

 Columellar margin vertical, making an angle with parietal wall, 

 which bears a slight film of callus. Alt. 18 ?, diam. 7 mill. ; some- 

 times narrower. 



^[<>l^ltf<l!>l* near TnijiUo, Pern (Cuming). 



Bitlliin* fnrr!f n* BROD., P. Z. S., 1832, p. 106. SOWB., Conch. 

 Illustr., f. 31. Bitlimu* tnn-lt.ii* DESK., in Lam. An. s. Vert., viii, 

 p. 275. REEVE, Conch. Icon., pi. 20, f. 124. PER., Monogr., ii, 

 p. 178 ; vi, p. 118. 



The closely reflexed and appressed columellar margin leaving but 

 a narrow chink-like perforation, and the regularly tapering spire 

 are characteristic. In young shells the columellar reflexion is 

 shorter. The bands are often more or less interrupted into spots ; 

 the basal band is wider; and there is occasionally a short fifth 

 band immediately at the base. Some specimens are larger than 

 above indicated, alt. 26, diam. 7J mill. 



The only known locality for this species lies considerably north 

 of the range of other slender Bostryx forms. 



Section 6. Geoceras Pilsbry, 1896. 



Shell cylindrical or column-shaped, long (the diam. less than one- 

 fifth the alt. in known species), imperforate or nearly so, with many 

 (16-19) narrow whorls, the base of the last defined by an angle or 

 keel. Aperture small, the outer lip unexpanded, columellar lip 

 somewhat dilated, appressed. Type B. colnmeHarl* Reeve. 



A group of the Peruvian Andes, somewhat resembling Holospira 

 in the narrow and numerous whorls. 



B. COLUMELLARIS Reeve. PI. 45, fig. 6. 



Shell imperforate, ci/f!n<l >!<</?, rather solid, obliquely striatulate, 

 shining; bluish flesh-color. Spire long. Whorl* 17, slightly con- 

 vex, the first 7 forming a cone with rather acute, corneous apex, 

 the rest of the whorls subequal ; last whorl one-sixth the length of 

 shell, obtusely carinated below the middle. 



Aperture little oblique, subtetragonal-oval ; peristome simple, un- 

 expanded, the columellar margin reflexed and adnate. Columella 

 somewhat twisted. Alt. 33, diam. scarcely 6 mill.; aperture 6 mill, 

 long. (P/V.). 



