198 MOLLUSCA. 
H. and A. Adams? to include a larger number of American species. The structure 
of the jaw and radula was used by myself in 1873 ? as a distinctive character by which 
to separate Otostomus from Bulimulus, and afterwards‘ I gave a list of the species. 
Fischer and Crosse, two years later ®, established essentially the same division, based on 
the same characters, under a new name. 
The great majority of the Mexican and Central-American species which have been 
described formerly as belonging to the old genus Bulimus appertain to this division, 
and also a large number of South-American species, as well as some Caribbean ones. 
They have been distributed among several subgenera by Albers and by H. and A. 
Adams, but it is very difficult to fix the limits of them: if one relies on such 
distinctive characters of the shell as can be indicated by a few words, very dissimilar 
shells will be included in one subgenus ; and if one groups together the species which 
are linked one to the other by gradual affinities and general resemblance of the whole 
aspect, it is almost impossible to give precise characters for such groups. 
The Mexican and Central-American species can be arranged in groups as follows :— 
a. Rather large species, with sculptured shell and coloured, dombeyanus, fenestratus, lilacinus, 
broadly expanded aperture. zhorquinensis. 
6. Elongated, nearly smooth, with broadly expanded aper- 
ture. . . 2. . e . ~ 2 + « « yosephus, serperastrum. 
c. More or less oval, nearly smooth, with large, broadly delattrei, chiapensis, _castus, 
expanded aperture. angasi. 
d. Elongated or oval, longitudinally wrinkled or striated, dunkeri, sulcosus, rudis, ghies- 
with narrowly expanded aperture. breghti, hegewischi, jonasi, lirinus, cucullus. 
e. Similar to the preceding in form and general appear- 
ance, butsmooth . . .. ... . . . . . aurifluus, recluzianus. 
f. Oblong or elongated, nearly smooth, variegated with fenestrellus, attenuatus, trimaria- 
dark spots, more or less shining; aperture narrowly nus, hepatostomus, costaricensis, 
expanded. pluvialis, bugabensis, sargi, droueti, inglorius. 
g. Oblong, variegated with spiral rows of spots or pale maculatus, totonacus, championi, 
bands ; aperture straight or very slightly expanded. emeus, ? dominicus. 
h. Oval, with reticulated spiral bands and straight coloured 
aperture . . . . ‘wmazuensis, tripictus. 
2. Oblong or elongated, conspicuously spirally striated, 
unicolorous, yellow or white; aperture straight or 
slightly expanded . . . . . . . . sulfureus, moricandi. 
k. Oblong, smooth, variegated ; aperture straight, 
aa. Withspiralbands. . .....4.2.~, moritinctus, livescens, discrepans, 
alternans, honduranus, tryoni, tropicalis, uhdeanus. 
6b. With longitudinal streaks, sometimes obsolete . multilineatus, heterogeneus, semi- 
pellucidus, panamensis. 
