50 HELTCID^. 



CERASTUS, Albers, 1860. Shell rimate, ovate, costulate or 

 striulate, thin, corneous ; whorls 6-7, somewhat convex, the last 

 as long as the spire; aperture rounded -ovate ; peristome 

 reflected, with approaching margins joined by a thin callus. 

 B. distans^ Ffr. 13 sp. India, E. Africa. 



HAPALUS, Albers, 1850. (Harpalus, Austin, 1872.) Shell 

 imperforate, elongated, very thin, transparent; whorls six or 

 seven, the last more than half the total length ; columella 

 callous, twisted above ; aperture oval, angular above ; peristome 

 simple, sharp ; outer lip arcuated above. B. Grateloupi, Pfr. 

 17 sp. India, East Indies, Philippines, Guinea, etc. 



RAPHIELLUS, Pfeiffer, 1855. B. achatinellinus^ Porbes. Gala- 

 pagos. 



BuLiMULUs, Leach, 1814. ' 



Syn. — Peristoma, Kryn., 1833. Zebrina, Held, 1837. 



Distr. — 545 sp. Tropical America. 



Shell oblong, aperture longitudinal, edentulate, peristome thin, 

 margins imequal; columella integral. Jaw arcuate, closely 

 plicate. Lingual membrane (of B. dealbatus) broad, central 

 teeth tricuspid, the median cusp very long ; laterals bicuspid; 

 the dentition A^aries in the ditlerent groups. 



The following sections form the subgenus : — 



GONIOGNATHMUS, Crosse and Fischer, 1875. It is characterized 

 by a jaw having plications that are angulated in the centre, and 

 by lingual teeth with narrow inner cuspidation, nearly as long- 

 as the median cusp, which is obtuse and broad. 



Eudioptus, Albers, 1860. Shell imperforate, ovate or ovate- 

 oblong, smooth, shining, pellucid, thin; whorls 5-6, the last 

 exceeding the spire ; aperture ovate or ovate-oblong ; columella 

 strict, thin ; peristome acute, simple. G. pseadosuccinea, Moric. 

 6 sp. South America. 



PlectostyluSj Beck, 1837. Shell imperforate, thin, translucent, 

 conic-oval ; spire acute ; columella intrant, slim ; peristome 

 thin, sharp. B. Chilensis, Lesson (xcviii, 27). 18 sp. South 

 America. 



Drymseus, Albers, 1850. (Hamadr3'as, Albers, 1850.) Shell 

 perforated or nmbilicated, oblong, lightl}?^ striate or rugose ; 

 spire elongated, sharp ; whorls seven or eight ; aperture oblong- 

 oval ; columella subtortuous ; peristome simple ; columellar lip 

 reflected. B. xanthodomus^ d'Orb. (xcviii, 28). 100 sp. Mexico, 

 Central and South America, West Indies. 



Leiostraciis, Albers, 1850. Shell thin, perforated, oblong- 

 conic, shining ; spire elevated, apex acute ; whorls seven or 

 eight ; aperture oval or oblong-oval ; peristome thin, more or 

 less expanded ; columellar lip dilated, reflected. B. Mexicanus^ 

 Lam. (xcvii, 20). 38 sp. Florida, West Indies, Mexico, So. 

 America. 



