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Show 262 ISLAND LIFE. [rAR'r n. undistincruished series. It appears too, that the late Governor, Major-G~neral Lefroy, "has sown and distribu.ted throughout the islands packets of seeds frorp. Kew, representmg no less than 600 species, principally of trees and shrubs suited. to san~y coast soils" -so that it will be more than ever d1fficult 1n future years to distinguish the indjgenous from the introduced vegetation. From the researches of Dr. Rein and Mr. Moseley there appear to be about 250 flowering plants in a ':ild. state, and of these Mr. Moseley thinks less than half are md1genous. The majority are tropical and West Indian, while others are common to the Southern States of North America; the former class having been largely brought by means of the Gulf Stream, the latter by the agency of birds or by winds. Mr. Jones tells us that the currents bring numberless objects animate and inanimate from the Carribean Sea, including the seeds of trees, shrubs, and other plants, which are continually cast ashore and sometimes vegetate. The soap-berry tree (Sapindus saponaTia) has been actually observed to originate in this way. Professor Oliver informs me that he knows of no undoubtedly distinct species of flowering plants peculiar to Bermuda, though there are some local forms of continental species, -instancing SisyTinchium, Bermudianum and Rhus toxicodendTon. There are however, two ferns-an Adiantum and a N epbrodium, which are unknown from any other localjty, and this renders it probable that some of the flowering plants are also peculiar. The juniper, which is so conspicuous a feature of the islands, is said to be a West Indian species ( J unipettu.s baTbadensis) found jn Jamaica and the Bahamas, not the North American red cedar ; but there seems to be still some doubt about this common plant. Mr. Moseley, who visited Bermuda in the ChallengeT, has well explained the probable origin of the vegetation. The large number of West Indian plants is no doubt due to the Gulf Stream and constant surface drift of warm water in this direction, while others have been brought by the annual cyclones which sweep over the intervening ocean. The great number of American migratory birds, including large flocks of the American golden plover, with ducks and other aquatic species, no doubt CHAP. XII.] BERMUDA. 263 occasionally bring seeds, either in the mud attached to their feet or ~n their stomachs.1 As these causes are either constantly in act10n or recur annually, it is not surprising that almost all the species should be unchanged owjng to the frequent intercrossincr of freshly-arrived specimens. If a competent botanist wer: thoroughly to explore Bermuda, eliminate the species introduced by human agency, and investigate the source from whence the others were derived and the mode by which they had reached so remote an island, we should obtain important information as to the dispersal of plants, which might afford us a clue to the solution of many difficult problems in their geographical distribution. Concluding R emaTlcs.-The two groups of islands we have now been considering furnish us with some most instructive facts as to the power of many groups of organisms to pass over from 700 to 900 miles of open sea. There is no doubt whatever that all the indigenous species have thus reached these islands, and in many cases the process may be seen going on from year to year. We find that, as regards birds, migratory habits and the liability to be caught by violent storms are the conditions which determine the island-population. In both islands the land-birds are almost exclusively migrants; and in both, the non-migratory groups-wrens, tits, creepers, and nuthatches-are absent ; while the number of annual visitors is greater in prop~rtion as the migratory habits and prevalence of storms afford more efficient means for their introduction. We find also, that these great distances do not prevent the immigration of some insects of most of the orders, and especially of a considerable number and variety of beetles; while even land-shells are fairly represented in both islands, the large proportion of peculiar species clearly indicating that, as we might expect, individuals of this group of organisms arrive only at long and irregular intervals. Plants are represented by a considerable variety of orders and genera, most of which show some special adaptation for dispersal by wind or water, or through the medium of birds; and there is 1 "Notes on the Vegetation of Bermuda,'' by H. N. Moseley. (Jou1·nal of the Linnean Society, Vol. XIV., "Botany," p. 317.) |