GEOGIIAPHICAL DISTRIBUTION HCj 



of its most southern portion, including the islands of the 

 coast, has demonstrated that many of the land-moUusks 

 indigenous to Cuba, arc found both on the main land and 

 the islands, and that others ■which are derived from a more 

 distant som'ce, also exist there. Among the former are 

 Pupa incajia, Cylindrella lactaria, Cyclostoma dentatum, 

 Bulimiis itndatus and fasciafus ; and among the latter, 

 Bulimus virgulatus, and Selix rJiodocheila, selenina, 

 ottonis, &c. There are other species which, so far as is 

 at present ascertained, are peculiar to this section. Such 

 is Vaginulus fioridanus. Dead and Avorn specimens of 

 other Cuban species are also sometimes seen in collec- 

 tions, and represented to have been procured in Florida, 

 but the evidence that they actually -were, is not entirely 

 satisfactory. 'The other species indigenous to this sec- 

 tion are the same which are found in the next northern 

 section. The influence of a mild climate approaching 

 that of the intertropical regions, and very favorable to 

 the multiplication of species, is counteracted, in some 

 degree, by the excessive humidity of large tracts, and 

 by the general prevalence of a sandy soil. For this 

 reason, though in some situations they exist in multitudes, 

 there are extensive portions where it is almost impossible 

 to discover a single one ; and, in general, it may be said, 

 that individuals are multiplied whilst species are re- 

 strained. The marked characteristics of this section, 

 and its near approach to a tropical clunate, lead us to 

 expect that when it shall have been thoroughly explored 

 it will be found to contain more than the tAventy-eight 



