CHAP. XIV.] THE NEOTKOPICAL REGION. 77 



It is probable that the three chief islands, Cuba, Jamaica and 

 Hayti, are nearly equally rich in land-shells; but the last is 

 very much less known, and therefore, perhaps, appears to be 

 much poorer. Cuba has rather more species than Jamaica ; 

 but while the former has only 1 peculiar genus {Diplopoma), 

 the latter has 3 (Geomelania, Chittya, and Jamaicea), as well as 

 two others only represented in the other islands by single 

 species. From Hayti, only about one-third as many species are 

 known as from the two former islands. It has no peculiar 

 genera, but it has some forms in common with Cuba and others 

 with Jamaica, which show that those islands have more connec- 

 tion with it, than with each other ; just as we found to be the 

 case in birds. Portorico and the Virgin islands have still fewer 

 species than Hayti ; and, as many of the genera common to the 

 other three islands are wanting, there is, no doubt, here a real 

 deficiency. In the islands farther south (Barbuda to Martinique) 

 more Antillean genera disappear or become very rare, while 

 some continental forms take their place. The islands from St. 

 Lucia to Trinidad have a still more continental character ; the 

 genus Bulimus, so largely developed on the continent, only 

 reaching St. Lucia. The Bahamas contain about 80 species of 

 land-shells, of which 25 are Antillean, the rest peculiar ; all the 

 genera being Antillean. The affinity is chiefly with Hayti and 

 Cuba, but closest with the latter island. 



In the West Indian islands as a whole, there are 11 peculiar 

 genera ; 9 operculate {Oeomelania, Chittya, Jamaicea, Licina, 

 Choanopoma, Ctenopoina, Diplopoma, Stoastoma, Lucidella) ; and 

 2 inoperculate {Sagda and Stenopus), besides Cyclostomus, 

 which belongs to the Old "World and is not found on the 

 American continent. Mr. Bland considers, that many of the 

 Antillean land-shells exhibit decided African and Asiatic, rather 

 than South American affinities. A species of the Asiatic genus 

 Diplommatina has been found in Trinidad, and an Indian 

 species of Ennea occurs in Grenada and St. Thomas ; a clear 

 indication that land-sheUs are liable to be accidentally imported, 

 and to become established in the less productive islands. 



Although these islands are so wonderfully rich even now, 



