164 PLANTS, SEEDS, AND CURRENTS 



A section of one of the seeds disclosed traces of two cells, each 

 holding an embryo and displaying a large shrinkage- cavity. 



Mangifera indica (Mango) 



The empty fibro-membranous " stones " of this fruit are common 

 on the beaches of the Turks Islands and in West Indian beach-drift 

 generally. I would imagine that those washed ashore on the Turks 

 Islands were drifted there from San Domingo or were thrown over- 

 board from passing vessels. Numerous small craft hailing from San 

 Domingo and other islands trade in fruit in these seas. These 

 materials are found all over the tropics on the beaches of countries 

 where the Mango is cultivated. No doubt they often occur on other 

 coasts derived from rubbish thrown over by passing ships. Prof. 

 Ewart tells me that they are cast ashore on the south coasts of 

 Australia; and in Chapter II. reference is made to one that was 

 stranded on the coast of South Wales. 



Miscellaneous Materials in the Beach-drift of the Turks 



Islands 



Amongst these materials may be specially noticed large spines or 

 prickles, pumice, floating corals, and electric-light bulbs, the second 

 and third named deriving special interest from their suitability for 

 carrying small seeds in their cells or crevices. 



The large Prickles of Zanthoxylum. — These large spines or prickles, 

 which are rather frequent in the drift, are conical in form, and are 

 apparently detached from the trunks of two species of Zanthoxylum, 

 a genus including different West Indian trees. The largest prickles 

 have a diameter at the base of two to two and a half inches, and 

 belong perhaps to Z. clava-Herculis, the " Prickly Yellow " of the 

 Jamaican. The smallest kind has a basal diameter of one and a half 

 inch. These prickles would be able to withstand the transatlantic 

 passage, and ought to be found amongst the West Indian drift 

 stranded on European beaches. They are figured by Sloane (Vol. II., 

 table 172), though not in connection with drift, under the name of 

 Euonymus affinis, a tree which, he says, is very common in Jamaica. 



Pumice. — The stranded pumice usually consists of small, rounded 

 pebbles, a quarter to a half inch across, which commonly occur 

 amongst the smaller drift sorted out by the waves above the line of 

 the heavier and larger drift. Occasionally one finds large fragments, 

 as in the case of one washed ashore on the east coast of Grand Turk, 

 which was seven and a half inches long and weighed one and one- 

 eighth pound. It was well rounded, and was partially incrusted 

 with large Serpulid tubes, 5 to 6 mm. in diameter, and with other 

 marine organisms. Evidently it had been a year or more afloat, and 

 might well have been transported from the other side of the Atlantic. 



Floating Corals. — Fragments of floating corals stranded on the 

 beaches of Grand Turk and of the other cays, as well as on the shores 

 of the neighbouring Caicos Islands, are well known to the residents, 

 and are termed " floating stones." Occasionally they are picked up 



