1894. 



PROCEEDINGS OF THE NATIONAL MUSEUM. 427 



Seeing, moreover, the greater number of both genera and species, absolutely and 

 proportionately in the islands under consideration, it may not unreasonably be sug- 

 gested that the insular stamp has ratiier been impressed on the fauna of the con- 

 tinent than the reverse. 



Since the time of Bland's studies the discovery of many new species, 

 a better knowledge of their distribution, the great progress made in 

 classification, and in the soundings of the Caribbean, the Gulf of Mex- 

 ico, and the adjoining i)arts of the Atlantic, tlie added knowledge of 

 the currents and winds, as well as the advances made in the study of 

 tlie geology and paleontology of this general region go to confirm the 

 above statement, and in the direction of proving that the land molluscan 

 fauna of the greater archipelago is largly a peculiar one»; that it devel- 

 oped in part in the region it now occupies, and that it has spread, to 

 some extent, to Florida, the Bahamas, Mexico, Central and South 

 America, and the Lesser Antilles, by some of the means I have men- 

 tioned above. 



Some 28 genera and subordinate groups of land mollusks are con- 

 fi!ied strictly to the Greater Antilles, and no less than 24 more have 

 here their metropolis, or greatest numerical development of species. 



It has been claimed that there has never been land connection 

 between the islands of this archipehigo, and that the homogeneousness 

 of its land and fresh w^ater molluscan fauna could be accounted for by 

 supposing that many of the species had been carried from island to 

 island, by storms or currents, or that they had been transported by other 

 means. While no doubt a small proportion of the forms have thus 

 migrated, yet the number of species common to two or more islands is 

 so small, and the distribution of many of the genera and subordinate 

 groups is so peculiar, that I believe we are not justified in explaining 

 the present distribution by such an hypothesis. Cuba, with nearly 700 

 species of land and fresh- water mollusks, has only 53 not confined to the 

 island; Jamaica, with over 500 species, has 41; Haiti, with 270 species, 

 has only 30; and Puerto Rico, with 130 species, has 34 stragglers to 

 other localities.* 



Now, it is very remarkable that while many species of non-operculate 

 land snails are common to the Greater ^Vntilles and the continent, as 

 well as to several of the different Lesser Antilleau islands, not a single 

 operculate is known to inhabit both the greater archipelago and the 

 maiidand of tropical America. Two species, Chondropoma dentatum and 

 Helicina subglohulosa, and possibly a third, Ctenopoma riigulosum, all 

 Cuban forms, are colonized in the extreme southern end of Florida, 



" Haiti — and under this name I include the whole island — has an area of 28,000 

 square miles, yet only about one-half as many terrestrial and Huviatile mollusks are 

 known to belong to it as are found in Jamaica. With a very diversified surface, an 

 abundance of forest and rainfall, and a large area of limestone, it is probable that 

 when it is fully explored the number of its land and fresh water mollusks will be 

 doubled, and many interesting points of geographical distribution will be brought 

 to light. 



