HELICIDA. 53 
Leptomerus, Albers, 1850. Shell thin, subperforated or very 
rarely imperforate, oval or oblong-conic; whorls 5-7, slightly 
inflated below; aperture oval or oblong, shorter than the spire ; 
columella usually subarcuated; peristome simple, thin and sharp ; 
columellar lip a little reflected. B. Meridanus, Pfr. (xevii, 19). 
52 sp. South and Central America, West Indies. 
Nesiotus, Albers, 1850. (Omphalostyla, Schlutt., Ads., 1855.) 
Shell subperforate, oval-conic or oblong-turreted, longitudinally 
striated ; whorls 6-8; aperture oblong, angular at base, one-third 
the leneth of the shell, columella vertical; peristome simple, 
sublabiate within; lips subparallel, united by a small callus ; 
columellar lip dilated above. B. rugiferus, Sowb. (xeviii, 35). 
16 sp. Galapagos Isles. 
Rhabdotus, Albers, 1850. Lip not expanded nor reflected. B. 
dealbatus, Say (xeviii, 34). 65 sp. Alabama, L. Cal., Mexico 
to South America. 
Pleuropyrgus, Martens. Shell imperforate, turreted, rather 
solid, with obtuse ribs; whorls fifteen, convex; aperture semi- 
oval; peristome simple, the margin shortly expanded. B. Chem- 
nitzioides, Forbes. Galapagos Isles. 
BosTRYX, Troschel, 1847. Shell turreted, scalariform, with 
wide umbilicus; whorls six, the first four regular, the last two 
shouldered, bicarinated; aperture subquadrangular; peristome 
simple or slightly expanded, continuous. 8B. solutus, Troschel 
(xevii, 22). 5 sp. South America. 
PLACOSTYLUS, Beck, 1837. Shell imperforate, oblong, conical, 
longitudinally striate; last whorl longer than the spire; aperture 
oval-oblong, irregular, angular above; columella a little arcuated, 
callous; columellar lip wide, peristome thick, lips united by a 
wide callus, shining and usually dentate or tuberculate.  B. 
insignis, Petit (xevii,6). 58 sp. Australasian and Polynesian. 
Euplacostylus, Crosse. Hdge of aperture thickened. Animal 
with hinder part of body obtuse. B. fibratus,Martyn. Terres- 
trial. New Caledonia, Solomon’s and Fiji Isles. 
Charis, Albers, 1850. B. fulguratus, Jay. Fiji Islands. 
Apastus, Albers, 1850. Shell imperforate, fusiform, thin, 
diaphanous, lightly striate; whorls six, rapidly enlarging, the 
last longer than the spire; aperture oval-oblong, rounded at the 
base; columella subarcuated; peristome labiate, reflected, lips 
united by a thin callus. B. miltocheilus, Reeve (xevii, 7). 
Solomon Isles. 
AMPHIDROMUS, Albers, 1850. (Beddomea, Nevill.) Shell 
dextral or sinistral, perforate or covered, ovate-conical or oblong- 
ovate; whorls 6—74, scarcely convex ; columella dilated, twisted, 
receding; aperture oblong, semiovate; peristome thickened, 
expanded, reflected, outer margin arcuate. Jaw feebly ribbed ; 
dentition like Orthalicus. B. perversus; Linn. 47 sp. Java, 
Siam, ete. 
