162 PROCEEDINGS OF THE ACADEMY OF 
I give in fig. 5 a general view of the arrangement of the teeth 
in Zonites.. The centrals have a base of attachment longer than 
wide, subquadrate, with lateral expansions at the corners of the 
lower margin. The reflected portion varies in size in the various 
species, from highly developed in wirzdulus (pl. X VIL., fig. 6) and 
others, to slightly developed in lasmodon (pl. III., fig. 7) and 
others ; in the latter case resembling the short reflection of Vitrina. 
The reflection always bears a more or less developed central 
cusp, generally reaching to or beyond the lower margin of the 
base of attachment, and always bearing a distinct cutting point, 
which last, like the cusp, is usually slender, and projects over the 
tooth of the adjoining transverse line. The side cusps of the 
reflected portion of the tooth are usually subobsolete, but they are 
distinctly developed in Z. lasmodon (pl. IIL., fig. 7), suppressus (pl. 
XVIL., fig. 11), Gundlachi (pl. III., fig. 10), capsella (fig. 4), gularis 
(fig. 1), arboreus (pl. XVIL., fig. 4), cellarius (pl. II., fig. 3), leevi- 
gatus (fig. 1, 2), stgnificans (pl. XVII., fig. 10), ferreus (pl. XVILI., 
fic. 9), viridulus (pl. XVII., fig. 6), netidus (pl. XVII., fig. 7), 
fulvus (pl. XVIL., fig. 5), melewm (pl. XVII., fig. 8). On the side 
cusps are distinctly developed cutting points in all the species I 
have examined, excepting levigatus and cellarius, in which I find 
no trace of cutting points. These points when present vary in 
development in the various species, generally disposed to be tri- 
angular and somewhat aculeate in form, thus bearing a resem- 
blance to the cusp of the marginal teeth. The greatest develop- 
ment of these cutting points is seen in Z. capnodes (pl. II., fig. 6; 
pl. III., fig. 12). Ihave given on pl. III., fig. 12,an enlarged view 
of a central in Z. capnodes; abcd gives the base of attachment, 
e the reflected portion of the tooth, f f the subobsolete side cusps, 
h the median cusp, 2 the cutting point of the median cusp, g g 
the cutting points of the side cusps. The general outline of the 
central tooth is graceful and slender as compared with the other 
genera, except Limax and Vitrina. 
The lateral teeth in Zonites are of the same type as the central 
but are rendered unsymmetrical (as usual in the land shells) by, 
the suppression of the inner, lower, lateral expansion of the base 
of attachment and the inner side cusp and cutting point. It is 
1 The characters of the separate teeth of this species are better shown in 
pl. XVII., fig. 3. 
