52 University of Michigan 
acters, Guppya championi von Martens, G. browni Pilsbry, and 
G. costaricana Pilsbry, with the variety elatior Pilsbry, appear 
to belong in this group. All of these species are large shells 
with weak spiral and radial striation and rather rapidly 
increasing whorls. 
On the basis of the radula alone, Euconulus would certainly 
become a subgenus of Habroconus, and the latter would be 
separated genericly from Guppya. However, Crosse and 
Fischer (1872) remark: “After M. Bland (in letter), it fol- 
lows from a verbal communication made to him by Dr. 
Berendt, who had occasion to examine in living state Helix 
selenkai, that that mollusc possesses, at the posterior extremity, 
a mucous pore quite (tout ad fait) close to that of Stenopus”’ 
(translation). This appears to indicate a closer affinity with | 
Guppya, although Euconulus also has a mucous pore. 
In addition, Euconulus is a Holarctic genus, and in general 
the American forms decrease in size towards the south. (From 
the shell characters, I think it probable that G. micans Pilsbry 
and G. jalisco Pilsbry also will be found to belong in Euconu- 
lus.) Guppya, on the other hand, is a neotropical genus, whose 
forms (for example, G. vacans, G. gundlachi and G. sterkii) 
tend to decrease in size toward the north—that is, in the oppo- 
site direction. This appears to indicate a northern center of 
origin for Euconulus and a southern one for Guppya. Habro- 
conus only has, as far as known, neotropical species, which 
are larger than any of the American forms of Fuconulus. 
For these reasons, Habroconus is tentatively used here as a 
subgenus of Guppya, while the more familiar Euconulus is 
retained as a genus to include the conical forms with better 
developed radial striations, and with all of the well-developed 
marginals bicuspid. From the shell-characters, I rather doubt 
if the acutely carinate species with practically no spiral stria- 
