FOREIGN DRIFT OF THE TURKS ISLANDS 159 



Drepanocarpus lunatus, Mey. 



This shrub grows in maritime swamps in the tropics of the New 

 World and of the West Coast of Africa, being in both regions often 

 associated with the mangroves, and especially on the African side, 

 where, as we learn from Dr. Vogel's journal (Hooker's Niger Flora, 

 1849), it is frequent at the coasts and in the estuaries. According 

 to Grisebach it is found on the mainland of the New World from 

 Mexico to Brazil, and he records it from the West Indian islands of 

 Haiti, St. Lucia, and St. Vincent. In West Africa it thrives on the 

 Guinea Coast and in Senegal. 



With the exception of a solitary empty pod that came under my 

 notice on one of the beaches of the Turks Islands, I never found the 

 fruit represented in West Indian drift, nor was it represented in the 

 collection of Jamaican beach-drift made by Morris. It is therefore 

 probable that neither the fruits nor the seeds are suited for effective 

 dispersal by currents. Yet the opposite inference might be drawn 

 from the fact that out of about fifteen known species of the genus 

 only one occurs outside the New World, namely Drepanocarpus 

 lunatus, and that is held in common between West Africa and 

 America. De Candolle considered that this littoral species might be 

 spread by the currents, but gives no data. In his Geographic Botanique 

 (1855, circa p. 780) he viewed it as an American plant naturalised 

 in West Africa ; and with it he links Ecastaphyllum brownei, another 

 littoral plant that is both West Indian and West African, yet is 

 unsuited for trans-oceanic dispersal by currents (see p. 207). This 

 seems to be an unsatisfactory explanation. If valid, we should have 

 to apply it to other littoral plants, e. g. Symphonia globulifera, 

 which present precisely the same difficulty (see p. 243). 



Omphalea diandra, L. 



The seeds of this euphorbiaceous plant must be regarded as typical 

 of West Indian beach-drift. They are black, semi-globose, one to 

 one and a half inches across, and possess a hard, crustaceous shell. 

 Whilst scantily represented in the Turks Islands drift, they are 

 characteristic of the Trinidad beaches ; and they are included in the 

 collection of drift made by Morris on the coast of Jamaica (Chall. 

 Bot., IV., 302). But though about half of those collected by me on 

 the West Indian beaches contained kernels, the others being often 

 more or less empty, it is uncertain whether any of them would 

 retain their germinative capacity after prolonged flotation in sea- water, 

 the oily kernel being liable to a degenerative change that destroys 

 its viability after being kept for a year or two. The kernel removed 

 from its impervious hard shell floats in water, its buoyancy being 

 due mainly to the lightness of the albumen, but partly also to a 

 shrinkage- cavity between the cotyledons. It is thus apparent that 

 the seeds, which must often be carried down by rivers to the sea, 

 could be transported by the currents for considerable distances ; but 

 it is very doubtful whether this would aid the oversea dispersal of a 

 riverside inland plant such as Omphalea diandra undoubtedly is. 



