FOREIGN DRIFT OF THE TURKS ISLANDS 141 



its buoyancy for the many months that would be occupied in the 

 traverse. 



The other pods, which are about 4 inches long and roundish rather 

 than flat in section, hold about four seeds, enclosed in a similar dry 

 pulp, of which some float and others sink m sea-water. The remarks 

 above made concerning the fitness for being transported across the 

 ocean apply also to these fruits. As far as I know no Hymencea 

 pods have been recorded amongst West Indian drift on European 

 coasts. 



Carapa guiaxexsis, Aubl. 



Carapa as a littoral genus is linked with Rhizopkora not only in 

 its present distribution but probably also in its past associations. 

 Carapa, like Rhizopkora, with which it is often associated in coastal 

 swamp regions, has only a few species, the first-named possessing 

 only five or six and the last three or four. In both cases the genus 

 is mainly of the Old World, lending a species to the American conti- 

 nent which holds it in common with the African West Coast. In 

 both genera, therefore, the presumption is that the origin is Asiatic. 



Many critical questions of great importance are raised when we 

 come to discuss the distribution of these two genera, questions, I 

 may add, that were ably put by S chimp er years ago in his study of 

 the Indo-Malayan coast flora. Both, as already indicated, are littoral 

 genera, frequenting in the case of Rhizopkora coastal and estuarine 

 swamps exclusively, and in that of Carapa both the swamp and the 

 dry beach. In both cases there are two species that divide the 

 warm regions of the globe between them in the same peculiar fashion, 

 one appropriating America and the West Coast of Africa, the other 

 monopolising the rest of the tropical zone from the East Coast of 

 Africa eastward to the Western Pacific. In the instance of Rhizo- 

 phora there are not wanting localities where the Old World species 

 (Rk. mucronata) and the New World species (Rh. mangle) meet, as 

 in Fiji, a matter discussed at length in my work on Plant Dispersal. 

 As far as I can ascertain the two species of Carapa that hold the 

 Tropics between them never meet on common ground, C. guianensis 

 making its home in the warm regions of the New World and on the 

 tropical coasts of West Africa, and C. moluccensis ranging from 

 the Zambesi eastward to distant Fiji. [There is no need to raise 

 the question here whether C. moluccensis, Lam., is distinct from 

 C. obovata, Bl., another Asiatic form, since the distribution is much 

 the same, and the student of dispersal cannot distinguish between 

 the seeds of the two forms (see Chall. Bot., IV., 290).] 



Carapa guianensis is one of the features in the estuarine vegetation 

 of the large rivers of Brazil, the Guianas, and Venezuela, and occupies 

 a similar station in the adjacent West Indian island of Trinidad. 

 Its occurrence in the Orinoco estuary accounts for the presence of 

 so many of its seeds amongst the Orinoco drift on the south coast 

 of Trinidad. The tree is abundant in the Lower Amazon, as at 

 Para, and Spruce speaks of it as " met with all the way up the 

 Amazon " {Botanist on the Amazon, etc., edited by Wallace, 1908, 

 I., 480). I have not found, however, any reference to its occurrence 



