BERMUDA . 273 



cedar ; but there seems to be still some doubt about this 

 common plant. 



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. If a competent 

 botanist were thoroughly to explore Bermuda, eliminate 

 the species introduced by human agency, and investigate 

 the source' from whence the others w^ere derived and the 

 mode by which they had reached so remote an island, we 

 should obtain important information as to the dispersal of 

 plants, wdiich might afford us a clue to the solution of 

 many difficult problems in their geographical distribution. 



Ccndnding Manarks. — The tw^o 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 wdiatever 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 

 groups — wrens, tits, creepers, and nuthatches — are absent ; 

 while the number of annual visitors is greater in propor- 

 tion as the migratory habits and prevalence of storms 

 afford more efficient means for their introduction. 



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

 of the Linncan Society, Vol. XIV., Botany, p. 317.) 



T 



