1 72 BULIMULUS-BOSTRYX-LISSOACME. 



Group of B. derelidus. 

 Outer lip well expanded. Surface more or less decussated. 



B. DERELICTUS Broderip. PI. 48, figs. 91, 92. 



Shell with ample and deep umbilicus, ovate-conic, solid, opaque, 

 whitish with fleshy narrow streaks or conspicuous, corneous-brown 

 streaks interrupted with white flecks and striae, the brown sometimes 

 much predominating. Surface with growth-wrinkles and some 

 decussating spiral incised striae ; lusterless. Spire conic, concave 

 above, the apex mamillar, white or roseate, smooth. Whorls 6, con- 

 vex, the last subangular around the large umbilicus. 



Aperture ovate, oblique, over half the total length of shell, white 

 or fleshy within ; outer lip broadly expanded, somewhat flattened, 

 white. .Columella concave, columellar lip broadly dilated above ; 

 terminations of peristome much converging. 



Alt. 25, diam. 16 mill. 



Alt. 22, diam. 16 mill. 



Alt. 20}, diam. 12} mill. 



Cobija, Chili (Cuming, Orbigny, Paz). 



Bulinus derelidus BROD., P. Z. S., 1832, p. 107. SOWB., Conch. 

 Illustr., f. 38. Bulimus derelictus ORB., Voy. dans 1'Amer. Merid., 

 p. 306. PFR., Monogr., ii, p. 63 ; vi, 43. DESK, in Fer. Hist., p. 

 69, pi. 139, f. 4, 5. REEVE, Conch. Icon., f. 151. HIDALGO, Mol. 

 Viaje al Pacif., p. 88. POT. & MICH., Galerie, i, p. 139, pi. 14, f. 13, 

 14. Bulimus curtus KOCH, in Philippi, Abbild. u. Beschreib., i, p. 

 158, pi. 2, f. 8. 



Well distinguished by the oblique aperture, flaring, subreflexed 

 outer lip and mamillar apex. The latter is smooth, showing the 

 species to be a Lissoacme, not a Seutalus. 



B. UMBILICATUS Miller. PI. 48, figs. 93, 94, 95, 96. 



Shell umbilicated, ovate-conic or oblong-conic, thin, closely wave- 

 striate, with obsolete spiral lines, sometimes obsoletely carinated) 

 pale tawny, sometimes obscurely three-banded. Spire convex-conic, 

 attenuated above, the apex acute. Whorls 82, planulate, the suture 

 slight, at the last whorl crenulated and more distinctly separating ; 

 first whorl glabrous, the last whorl three-sevenths to one-half the 

 length of shell ; umbilicus perforated, columella straight, white. 



Aperture suboval, slightly oblique, white inside ; peristome simple, 

 thin, acute, the right margin narrowly expanded and reflexed, arcu- 



