440 WEST INDIAN MOLLUSES— SIMPSON. vol. xvii. 



This migration by currents and in some cases, no doubt, by winds 

 from tlie Greater Antilles to the Bahamas, has not been of long contin- 

 uation, for the reason that the last elevation of this latter archipelago 

 above the sea has been comparatively a recent one and therefore there 

 has not been time for the formation of new genera or subordinate 

 groups, and only for few valid species. Many of the forms are so 

 slightly differentiated that they can not be separated with any degree 

 of accuracy, and others have broken into endless variations, which 

 may be taken as an indication that the region has not been very long 

 colonized and that species are multiplying. 



Had this laud been connected with Cuba or Haiti since it was last 

 elevated above the sea it is probable that it would now be far richer in 

 genera and species than it is. 



TPIE TROPICAL LAND AND FRESH-WATER MOLLUSCAN FAUNA OF 

 SOUTHERN FLORIDA, AND ITS RELATION TO THAT OF THE 

 GREATER ANTILLES, MEXICO, CENTRAL AND SOUTH AMERICA. 



In southern Florida some 28 or more species of land and freshwater 

 mollusks occur, nearly all of which are now living in Cuba, while a few 

 belong in Mexico, 1 possibly in South America, 2 are found in the Baha- 

 mas, and 1 perhaps came from Trinidad.* 



This terrestrial and fluviatile population of southern Florida is in 

 all probability the result of recent migration, mostly by means of winds 

 and currents. Most of the speciesare confined to the lower chain of 

 keys or the extreme southern part of the peninsula. Chondropoma 

 dentatum extends a short distance nortli of Cape Sable, Bulimiilus inulti- 

 lineatus reaches Caximbas, and Liguus fasciatus has been doubtfully 

 reported as far north as the Caloosahatchee River. Guppya gitndlaehi 

 and the two Maeroceramus no doubt extend their range to at least the 

 middle of the State. Bulimulus dormani, Polygyra cereolus, Flanorbis 

 tumidns, and ^Sph(crillm cubense probably inhabit the entire peninsula, 

 and AmpuUaria deprcs.sa, which is a form of A. ealujiiiosa, extends into 

 Georgia. 



"^The following is a list of tho species: Thysanophora cwca, Gup., Trinidad; TJii/- 

 sanophora vortex, Pfr., Cul>a, Haiti, Puerto Rico, St. Croix, St. Thomas, Bermuda; Thy. 

 Sitnophova dloscorlcola, C. B. Adams, Jamaica, Puerto Rico, Mexico, Vieque; Stro- 

 bilops hubhardi, Brown, Jamaica; Hemitrochus varians, Mke., Bahamas*, Polygyra cere- 

 olus, Muhl, Bahamas, Bermuda, Cuba?; Guppya gundlacM, Pfr., Cuba, Puerto Rico, 

 St. Thomas; Orthalicus undatus, Brug., Mexico, Jamaica, Trinidad, Central.America; 

 OriliaUcus melanocheilus,Ya.\., Mexico; Liguus fasciatus, Mull., Cuba; MeJaniclla gra- 

 ciUima, Pfr., Cuba, St. Thomas, Bahamas; tSubulina octonoides, Orb., Cuba, Jamaica, 

 Puerto Rico, Vieque, St. John, Barbados, Grenada, St. Tliomas; Sjiiraxis suhula, Pfr., 

 Jamaica, Cuba, Barbados, Antigua, Puerto Rico, St. John, St. Thomas; Maeroceramus 

 gossei, Pfr., Cuba, Jamaica, Texas, Mexico; Macrocerumas pontificus, Gld., Cuba, 

 Mexico; Bulhnulus marielinus, l?oej, Cuba; BuUmuhis dorinatii, W. G. B., New Gre- 

 nada?: Bulimulus muUiliiieatus, Say, Yucatan, (juateniala, northern South America; 

 CyViudrella poeyana. Orb., Cuba; Cylindrella jejuna, Gld., Cuba; Cerion incana, 

 Biun., Cuba; Helidna subglohuJosa, Poey, Cuba; Chondropoma dentatum.. Say, Cuba; 

 Ctenopoma rugulosum, Pfr. 1, Cuba; Planorbis tumidus, Pfr., Cuba, Mexico, California; 

 AmpuUaria caliginosa, live, Mexico; Gundlachia aneyliformis, Pfr., Cuba; Spharium 

 cubense, More., Cuba; Mexico, Texas. 



