BULIMULUS-BOSTRYX-PERON^EUS. 145 



Distinguished from other species of the same group, by the insen- 

 sible tapering of the spire toward the apex, and cylindrical form 

 toward the base. The earlier three whorls are of a brownish -violet, 

 which fades out below, the latter two whorls being nearly pure 

 white. The umbilical region ordinarily has a trace of a russet zone. 

 The surface is engraved with irregular, flexuous stride, more pro- 

 nounced toward the sutures ; and there is a small number of brown 

 or corneous dots, scattered at random over the surface. 



B. LICHENORUM d'Orbigny. PL 46, figs. 34, 35. 



Shell elongated, turriculate, umbilicated ; striate or subrugose ; 

 whitish, longitudinally marbled with grayish-yellow, a reddish spot 

 on the last whorl near the mouth. Spire lengthened, subconic, the 

 apex obtuse. AVhorls 8, equal, suture flat. Aperture oblong, nar- 

 row, whitish, the lip thin, sharp ; columella thick, a little dilated, 

 in part covering the narrow and rather shallow nmbilicus. 



Alt. 15, diam. 5 mill. (Orb.}. 



Plains at the foot of the mountains of Cobija, on lichen- covered 

 rocks exposed to the sun. ( Orb.). 



Helix lichnorum d'ORB., Mag. de Zool., 1835, p. 20. NotBulinus 

 lychnorum d'Orb., Sows., Conch. Illustr., f. 81, 82. Bulimus lich- 

 enorum d'ORB., Voy. dans 1'Amer. Merid., p. 264, pi. 41, f. 9-11. 

 Cochlicellus lichenmn BECK, Index, p. 63. Bulimus lichenum PFR,, 

 Monogr., ii, p. 112 ; iii, 346. 



Allied to B. scabiosus, but distinguished by the white color mar- 

 bled with gray instead of brown, the less elongated form, and the 

 whorls of the spire are not swollen. 



B. SUBCACTORUM Pilsbry, n. n. PL 46, fig. 36 (enlarged). 



Shell oblong-turrited, umbilicate ; whorls 7, somewhat rounded, 

 smooth or finely striated ; columella reflected. Aperture rather 

 small, lip simple. Bluish- white, with a few oblique ashy streaks, 

 apex blackish. (Reeve). 



Chilon, Bolivia, under dead trunks of cacti (Bridges). 



Bulimus lichenorum REEVE, Conch. Icon., pi. 14, f. 83, not of 

 d'Orbigny. 



The dark apex, regular oblique streaks and apparent lack of a 

 brown spot behind the peristome, indicate that Reeve's shell is not 

 the true B. lichenorum of d'Orbigny. The localities,, moreover, are 

 widely separated. 

 10 



^^rrif**^ 

 UNIVERSITY 



