290 PLANTS, SEEDS, AND CURRENTS 



Halophytes grow in abundance on the muddy shores of the creeks 

 and salt-ponds of Grand Turk. The most frequent are Batis mart- 

 tima, Salicornia ambigua, and a species of Sesuvium, with a species 

 of Suceda in places, and Borrichia arborescens at the landward border 

 of the flats. 



The Introduced Plants of Grand Turk. — I need only refer here 

 to the plants of waste ground which the white man has spread over 

 the tropics, such as Argemone mexicana, Datura stramonium, Ricinus 

 communis, and Vinca rosea. One of the first things to attract the 

 notice of the stranger when he lands at the town is an extensive 

 bank of Calotropis procera on the sea-front. 



Endemism and Isolation in the Turks Islands. — The data at my 

 disposal only allow of a brief reference to this subject and in a 

 tentative fashion. The bathymetrical surroundings of the Turks 

 Islands are discussed in the chapter on the geology of this small 

 group. It is highly probable that as a unit in the great Bahamian 

 archipelago the Turks Bank has always maintained its isolated 

 condition. North and south the submarine slopes descend to depths 

 of 2000 fathoms and over. The broad trench dividing the Turks 

 Bank from the Caicos Bank on the west must be about 1500 fathoms 

 deep opposite the two banks ; but they are connected to the south- 

 ward by a " col " covered by 1500 feet (250 fathoms) of water. Yet 

 this is the only evidence of a former possible connection with existing 

 land-surfaces, since away to the eastward stretch three submerged 

 banks which, except on the Turks Group side, are surrounded by the 

 ocean's depths. In these respects the isolation of the Turks Islands 

 is typical of the eastern Bahamas, where the banks on which the 

 islands rise may be separated by depths of 1000 to 2000 fathoms. 

 Endemism ought, therefore, to be well displayed in the Bahamian 

 archipelago, more especially in the east; but it would be kept in 

 check by the monotony of the climatic, geological, and soil con- 

 ditions. It is exhibited in the plants, the land-molluscs, and the 

 reptiles, but with a special Bahamian impress. Several of the 

 plants first described from the Turks Islands have been found in 

 the neighbouring islands, and it seems likely that the leading feature 

 of the endemism of this small group is that which it shares with the 

 Caicos Islands and the two Inaguas. There has been constant 

 intercourse between them for the last two centuries and more, and 

 it may be that the aborigines during earlier periods aided in bringing 

 about the mingling of their respective floras. 



The Flora of the Turks Islands from the Standpoint of Dispersal. — 

 The plants fall conveniently into two groups, those of the shore and 

 those of the inland scrub. The former are not only found over the 

 West Indian region, but often also in the Old World. The latter 

 are all plants of the New World, some occurring also in the other 

 West Indian islands, others widely spread over the Bahamas and 

 confined to that archipelago, others confined to, but held in common 

 by, the Turks and Caicos Islands and the two Inaguas, and a few 

 restricted to the Turks Group. 



The shore plants found in the Old World include — 

 Avicennia nitida (Currents). 



