140 BULIMULUS-BOSTRYX-PERON^EUS. 



B. LACTIFLUUS Pfeiffer. PI. 45, figs. 15, 16. 



Shell similar to B. atacamensis but smaller, with 9J whorls; thin ; 

 opaque white or faintly buff, alternating with numerous corneous or 

 corneous-brown ragged, irregular streaks, as wide as the white streaks 

 or wider ; smooth, but slightly puckered under the sutures. Last 

 whorl compressed below, subangular around the small umbilical per- 

 foration. External coloration visible within the aperture, which is 

 contained 3J times in altitude of shell, and is rather more expanded 

 than in B. atacamensis; peristome thin, very narrowly expanded; 

 columellar margin dilated and subreflexed. 



Alt. 15, diam. 4*8 mill. (Specimens). 



Alt. 16^-17, diam. 41 mill. (Pfr.). 



Cobija, Chili (Paz ; Coll. A. N. S. P.). 



Bulimus lactifluus PFR., P. Z. S... 1856, p. 330; Monogr., iv, p. 

 407; Novit. Conch., p. 425, pi. 96, f. 13, 14. HIDALGO, Journ. de 

 Conchyl., 1870, p. 56. 



Some specimens are albino with orange-black apical whorls; in 

 others the apex is either dark or corneous. The species is very near 

 to B. atacamensis, but smaller, more variegated than is usual in that 

 form, and with the outer lip a trifle expanded. These differences, 

 however, may be merely varietal. Pfeiffer's specimens were a little 

 larger than those before me, and had 10 to 11 whorls. 



B. ATACAMENSIS Pfeiffer. PI. 45, figs. 17, 18, 19, 20. 



Shell rimate-perforate, long, tapering, the last two whorls of about 

 qual diameter ; rather thin ; opaque-white, with irregular brown or 

 corneous stripes, sometimes the white predominating ; apical whorls 

 corneous or dark. Surface slightly shining, smooth, faintly or not 

 puckered below the sutures. Whorls 10-11, a little convex, the last 

 compressed below, subangular around the small umbilical excava- 

 tion. 



Aperture narrow-ovate, contained about 3* times in length, but 

 slightly oblique ; peristome thin, acute, the outer lip not expanded, 

 columellar lip dilated above ; parietal callus very slight. 



Alt. 19, diam. 5? mill.; alt. aperture 5*2 mill. (Specimen). 



Alt. 19, diam. 5 mill.; alt. aperture 5f mill. (Pfr.). 



Paposo, Atacama Desert, Chili (Philippi). 



Bulimus atacamensis PFR., Malak. Bl., iii, 1856, p. 207 ; Monogr., 

 iv, p. 486. HIDALGO, Journ. de Conch., 1870, p. 57 ; 1875, p. 128, 

 pi. 7,f. 5. Bulimus longurio CROSSE, Journ. Conch., 1869, p. 184. 



