INTRODUCTION. XV 
where it extends, however, to the southernmost part of Brazil; a few forms 
occur in North America, the genus reaching to Georgia and ‘Tennessee. 
GLANDINA has its headquarters in Mexico and Central America, extending not quite 
so far southward, and a little further northward, than Helicina; it is repre- 
sented in the West-Indian Islands by the somewhat different groups of 
Varicella and Oleacina, s. str. 
STREPTOSTYLA is almost peculiar to Southern Mexico and Central America, having 
one species only, so far as at present known, in the more northern parts of 
Mexico, viz. S. novoleonis, very few in the northern parts of South America, 
and some not very characteristic forms in the West-Indian Islands. 
PotyGyra is North American as well as Mexican, and does not extend southward 
beyond Honduras. In the West Indies it seems to be confined to the larger 
islands of Cuba and Jamaica (P. paludosa). In North America most of the 
species are restricted to the Southern United States, a few extending to the 
Cumberland subregion (Tennessee and Kentucky), one, P. leporina, to Illinois 
and Indiana. 
ORTALICHUS is almost equally well represented in Mexico and Central America, the 
West Indies, and the northern part of South America, extending southward to 
about as far as the Amazon valley *. It is wanting in North America, except 
in the southern part of Florida, which belongs more properly to the West- 
Indian region. 
Orostomus (= Goniognathmus, Crosse, nec Bulimulus = Orthotomium) is mainly 
South American, extending to Southern Brazil and the Argentine Republic 
(0. papyraceus) ; but it is also well represented in Central America and Mexico, 
becoming less numerous in species in the West-Indian Islands, and wanting 
altogether in the United States. 
EycaLopium and Ca@LOcENTRUM are peculiar to Central America or the southern parts 
of Mexico, but they do not extend south of Guatemala, and are therefore absent 
from the South-American continent. 
Ho nosrira, with Epirobia, is also almost peculiar to Mexico and the northern half 
of Central America: Holospira, s. sty., extends as far north as Texas and 
* The Berlin Museum has received specimens of 0. phlogerus, d’Orb., from Dr. von Steinen, from the upper 
affluents of the Rio Xingu, where they are used by the Bakairi Indians as ornaments; and also some of 
O. pulchellus, Spix, from the collector Rohde, from the banks of the Rio Mondego, in Matto Grosso. 
