LAND REGIONS. 201 



erous carnivorous la,nd snails, nearly 100 species of which have 

 been catalogued by Crosse and Fischer, an assemblage of 

 agnathous gastropods nowhere else equaled. Bulimulus contains 

 14 species. The following genera are special to this province or 

 have their metropolis here : Strebelia, Glandina, Xanthon3'-x, 

 Coelocentrum, Eucalodium, Holospira, Berendtia, Tomoc^^clus, 

 Ceres, Proserpinella. 



21. Caribbean Region. 



The West Indian Islands offer the interesting spectacle of a 

 succession of localized faunas of incomparable richness, occu- 

 pying contiguous islands. The climate appears to be very 

 favorable to the multiplication of snails, the mean temperature 

 being 59°-78°, the annual rain-fall usually over 100 inches. 

 The most remarkable character of the mollusca of this region is 

 the great proportion of pneumonopomata or operculated land 

 shells, as well as the variety of generic types represented, some 

 of which, such as Geomelania, Chittya, Jamaicia, Licina, Choan- 

 opoma, Ctenopoma, Diplopoma, Stoastoma, Lucidella, do not 

 exist on the adjacent American continent. The operculated 

 mollusks constitute one-half of the entire number of mollusca of 

 Jamaica and Cuba, and a smaller, but relatively large proportion 

 in the other islands. 



A few West Indian shells are acclimated in the South of 

 Florida, eighteen species occur in Mexico and Yucatan, and 

 several are common to the Lesser Antilles and Venezuela ; on 

 the other hand several species of the surrounding faunas have been 

 introduced, leaving the enormous number of 1200 or 1300 species, 

 peculiar to the islands, many of which have an extremely limited 

 area of distribution, being sometimes confined not only to a 

 single island, but to a single valley, of the mountainous dist^-icts. 



The West Indies maj^ be grouped in accordance with the 

 character of their faunas as follows: 1, Bahamas; 2, Cuba and 

 Isleof Pines; 3, Jamaica; 4, Haiti and Navassa ; 5, Porto-Rico, 

 Vieque, St. Croix, St. Thomas, St. Johns, Tortola, Anguilla, St. 

 Martin, St. Bartholomew, Sombrero ; 6, Guadeloupe, Martinique, 

 Dominica, St. Christopher, Antigua ; 1, St. Vincent, St. Lucia, 

 Barbados, Grenada, Trinidad ; 8, Windward Islands, Curagoa, 

 Buen-Ayre. 



This grouping mainly corresponds with the depth of the sur- 

 rounding water, those islands which partake of a common fauna 

 being generally separated by water of no great depth, so that at 

 some former period of the world's history they may have been 

 connected or at least approximated more closely than at present. 

 — Bland, Proc Am. Philos. Soc, xii, 56. 



1. Bahamas. Out of 43 species, 29 are restricted to this 

 archipelago, including all the operculates. The continental 



