CHAP. XII BERMUDA 273 



The Sisyrinchium is hardly distinct from a North- 

 American species. There are three species of Sabal, 

 commonly called " palmetto," in the Southern States. 

 The sedge, however, is said to be allied to a St. Helena 

 species. 



Mr. Moseley, who visited Bermuda in the Challenger, 

 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 occasionally 

 bring seeds, either in the mud attached to their feet or in 

 their stomachs.^ As these causes are either constantly 

 in action or recur annually, it is not surprising that almost 

 all the species should be unchanged owing to the frequent 

 intercrossing of freshly-arrived specimens. In the first 

 edition of this work published in 1880, Professor Oliver of 

 the Kew Herbarium was not acquainted with a single 

 species of flowering plant really peculiar to Bermuda. 

 The researches of many botanists since that date have, as 

 we have seen, discovered five, and, considering the small 

 extent of the island and the fragmentary nature of its 

 flora and fauna, there is probably little chance of adding 

 to this number. 



Concluding Remarks, — The two groups of islands we 

 have now been considering furnish us with some most in- 

 structive 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 re- 

 gards 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 al- 

 most exclusively migrants ; and in both, the non-migratory 



^ " Notes on the Vegetation of Bermuda," by H. N Moseley. {Journal 

 of the Linnean Society^ Vol. XIV., Botany, p. 317. 



