1894. PROCEEDINGS OF THE NATIONAL MUSEUM. 445 



Pleurodonte, better known as Lucerna, is limited to Jamaicfi, as ig 

 Uurycratera. The section Polydontes is Cuban; Parthena and LnquilUa 

 are confined to Haiti and Puerto Rico, while Gonofttomop,sis, with a 

 single species, belongs in Martini(]ue, and Caprinus, better known as 

 DentellarUi, is a characteristic group of the Lesser Antilles, extending 

 into South America, but is not found in the Greater Antilles. Theli- 

 (lonius with a metro])olis in the Greater Antilles has three si)e(;ies 

 in the Lesser Antilles and South America. Not a species of the genus 

 Pleurodonte is common to the two regions. 



Another great genus found abundantly in all the islands of the 

 Northwestern Archipelago, Hemitrochus, is absolutely wanting in the 

 Windward Islands, as are also the smaller Cuban genus Polymita, the 

 Jamaican genera Sayda, Lucidella, and Neocyclotns, and CepoJis of Haiti 

 and Puerto Rico; though the latter genus has a single species m Cen- 

 tral America, and another in Peru. 



Maeroceramus* Liyuus, Cerion,i Vendreysia, Geomelaniu., Proser- 

 pina, Ctenopoma, Adamsiella, iMeyalomastoma, Colobostylus, Alcadia^ 

 Stoastoma, and Uutrochatella, Greater Antillean genera, are entirely 

 wanting in the Lesser group; while CylindreUa, Gland.ina, CisUila, 

 Choanojwnia, Chondropoma, and Tudora, all higldy characteristic of the 

 Northwestern Archipelago are but feebly represented by a few strag- 

 glers, mostly in the northern end of the chain. Three genera only 

 are peculiar to the Windward Islands; two with a single species each; 

 RJiodonyx in Martinique; AmphUmlima in Dominica, Guadeloupe, and 

 St. Kitts; and Pellicula with two species in Guadeloupe. 



The fact of the rather recent formation of these northern volcanic 

 islands, built upon an old submarine plateau, that of the comparativ^e 

 poverty of the species and genera of this archipelago, and of their sliglit 

 relationship to those of the northwestern group, all go to indicate that 

 the Anegada Channel has not in the lifetime of the present land snail 

 fauna been bridged. A few species, however, have passed, no doubt 

 by way of the sea or other means, from one group to the other, more 

 from the northern islands to the southern than the reverse, as might 

 be expected from the comparatively richer fauna of the former. The 

 current which flows from the Atlantic through this channel would not 

 probably favor the drifting of species from either archipelago to the 

 other, and this with the prevailing wind from the east-northeast would 

 naturally carry most of the land snails washed into the sea out into the 

 open water of the Caribbean, where they would perish. 



I do not think that anyone who at all carefully studies the land and 

 freshwater molluscan fauna of the Lesser Antilles can doubt that it is 



* One species M. su/natus is found in Anguilla. This island and St. Bartholomew 

 having each only a fe\y species, though south of the Anegada Channel, have a some- 

 what mixed land-snail fauna, partaking of the characters of those of both the 

 Greater and Lesser Antilles. That a few species might have drifted to these islands 

 from the abundantly stocked Northern Archipelago is not strange. Bland groups the 

 two with Puerto Kico. 



tOne species is found in Cura^oa, one of the Leeward Islands. 



