52 HELICID. 
oval, a third of the length of the shell; columella intrant or a 
little arcuated; peristome simple, expanded; columellar lip 
dilated. B. montivagus, d’Orb. (xeviii, 36). 26 sp. South 
America. 
Otostomus, Beck, 1887. Shell perforated, pyramidal, thin ; 
whorls four or five, the last angulated with a flattened base ; 
aperture elongated, oblique, subtriangular ; peristome reflected, 
the lips joined by acallus. B. auris-leporis, Brug. (xcvii, 13). 9 
sp. South American. 
Navicula, Spix,1827. B.navicula, Wagner (xevii,14). Brazil. 
Semiclausaria, Pfeiffer, 1855. B. semiclausus, Pfr. N. 
Grenada. 
Plekocheilus, Guilding, 1828. (Auricula, Swains., 1840. Cap- 
rella, Guild., 1825.) Shell searcely umbilicated, oval, fusiform ; 
aperture elongated-oval, angulated above; columella with a 
large fold; peristome thick and wide. B. auris-Silent, Born 
(xevii, 18). 28 sp. South America, West Indies. 
Goniostomus, Beck, 1837. Shell narrowly perforate, fusiform 
or oblong-conic, the last whorl attenuated to the base; aperture 
oblong, angulated at its extremities ; columella arcuated, sub- 
plicate; peristome reflected. B. goniostomus, Fer. (xevii, 10). 
Brazil. 
Anthinus, Albers, 1850. Shell narrowly perforated, oblong- 
conic; spire turriculated ; whorls six or seven, the last as long 
as the spire; aperture oval-oblong, violet-tinted within; colu- 
mella dentate or plicate; peristome wide; columellar lip expanded. 
B. Myersii, Sowb. (xevii, 11). 5 sp. South America. 
The following groups form the subgenus :— 
ORTHOTOMIUM, Crosse and Fischer, 1875. It is American, 
and is characterized by vertical folds on the jaw, which are 
narrower in the centre; inner cusp of the teeth very short. 
Leptobyrsus, Crosse and Fischer, 1875. B. spirifer, Gabb. 
Lower California. . 
Thaumastus, Albers, 1860. Shell imperforate or rimate, con- 
ically oblong, striulate, white strigated with fuscous; aperture 
oblong-oval, usually not half the length of the shell; columella 
distinctly twisted; peristome obtuse, simple or shortly expanded, 
columellar margin reflected, more or less appressed. 5. Hartwegi, 
Pfr. (xeviii, 31). 47 sp. Southern United States, Mexico, 
West Indies, South America. 
Hlobulinus, Crosse and Fischer, 1875. 8B. sufflatus, Gould. 
2sp. Lower California. 
Rhinus, Albers, 1860. Shell perforated, conical or oblong- 
conical, corneous, the epidermis mostly pubescent ; whorls 6-7; 
aperture semioval; columella dilated, subtwisted; peristome 
shortly reflected, white. B. heterotrichus, Moric (xcviii, 26 . 
9sp. Brazil, Venezuela, Ins. Trinidad. 
