12 STROPHOCHEILUS-BORUS. 



cc. Elongated; columella very long, straight; outer lip slop- 

 ing, grandis. 

 aa. Peristome white or nearly so. 



b. Aperture less than half shell's length, short, wide below, outer 

 lip dentate, auritus. 



bb. Aperture over half the length. 

 c. Outer lip broadly reflexed. 



d. Aperture narrow, outer lip broadly reflexed, subvertical ; 

 parietal callus thin-edged, spreading broadly low on um- 

 bilical tract; surface malleated, chionostomus. 

 dd. Aperture wide below ; outer lip sloping, parietal callus 

 not broadly spreading below ; surface with low spiral 

 cords, gummatus, intercedens. 

 cc. Outer lip narrow, thickened, not reflexed, evenly arcuate; 

 form short-oval ; surface finely malleated in diamond- 

 pattern, oosomus. 



III. Earlier whorls with even, close, fine rib-strise throughout. 

 a. Spire regularly tapering ; whorls moderately convex. 



b. Spire conical, moderately long and acute, 

 c. Peristome rose-color, shell brownish, 



oblong us and v eras* us. 



cc. Peristome and shell-substance white, v. tobagoensis. 



bb. Spire short, apex very obtuse, peristome rose, capillaceus. 

 a. Whorls convex, the antepenultimate bulging ; lip white, 



llchtensteini. 



IV. Earlier whorls with tubercles at the suture. 



a. Lip-ends not convex above ; alt. 50-60 mill. rosaceus. 



<ta. Lip-ends converging above. 



b. Suture of last whorl crenulated, color flesh-buff, lip reflexed. 



c. Form stout, ovate ; alt. 30-38 mill. crenulatus. 



cc. Form slender; alt. 27, diam. 16 mill. crenellus. 



bb. Suture of last whorl hardly crenulated ; whitish ; lip narrow 

 but much thickened. pachychilus, 



V. Earlier whorls without riblets or creuulation. 

 a. Shell slender, the lip flatly reflexed, bridgesi. 



aa. Shell globose-ovate, lip narrow. 



b. Alt. 25-30 mill. lutescens. 



bb. Alt. 42 mill. globosus. 



The unfigured B. cacopatensis Pfr. is not included in this key. 



