STROPHOCHEILUS-BORUS. 11 



Key to species of Borus. 



[XOTE. In this key, which is an ampliGed and modified form of 

 one given by von Martens, some difficulty will be found in distin- 

 guishing between sections I and II. In cases of doubt a species may 

 well be tried in both sections.] 



I. Earlier whorls with close, sharp, long riblets. 

 A. Peristome white, yellowish or pale brownish, 

 a. Aperture trapezoidal, rather short; shell stout, large. 



b. No very distinct angle between columella and parietal wall. 

 c. Large, 130-150 mill. alt. ; a nodule on parietal wall above, 



popelairianus. 



cc. Smaller, 95-105 mill. ; no nodule, huascari. 



bb. A distinct angle between columella and parietal wall, 



maximus. 



aa. Aperture narrower, rather pear-shaped ; shell slenderer, of 

 moderate size. 

 b. Body-whorl not noticeably granulated. 



c. Kiblets of last nepionic whorl unequal ; spire slender, lip 

 narrow, santacruzii. 



cc. Riblets subequal ; spire short, stout ; lip narrow 7 , thick, 



mathiusii. 



ccc. Shell heavier, lip broad, spire slender, lacunosus. 



bb. Body-whorl granulated throughout, durfeldti, hupeanus. 



AA. Peristome rose-red ; shell granulated throughout. 

 a. Shell solid, elongated, with rather slender spire, lip narrow, 



granulosus. 



II. Earlier whorls with wider, fold-like ribs. 

 A. Surface densely, microscopically striolate vertically through- 

 out. 



a. Body-whorl variegated with zigzag light or denuded markings, 



valenciennesi. 



aa. Body-whorl without such markings ; spire purple-brown with 



light suture, cantagallanus. 



AA. Surface without minute vertical, regular striolce; usually 



malleated. 

 a. Peristome rose colored. 



b. Lip narrowly reflexed ; alt. about 80 mill. bronni. 



bb. Lip broadly reflexed, alt. 108-153 mill. 



c. Compact, ovate, columella rather short, outer lip vertical, 



ovatus* 



