ii8 Natural History Bulletin. 



southern coast for marine biological work. The richness of 

 the surface and shallow-water fauna is astonishing. Our 

 expedition did no dredging in the adjacent deeper water, but 

 a few hours' work in dredging across the channel on the inside 

 of Garden Key was amply repaid. Here, too, it is possible ta 

 study coral islands in their incipiency, as it were, and the com- 

 parison of the faunai of the various Florida Keys from Cape 

 Florida to the Tortugas should 3'ield a complete demonstra- 

 tion of some of the fundamental laws of geographical distribu- 

 tion. It would be most instructive, for instance, for a compe- 

 tent entomoloi^ist to undertake such an examination, confininc*" 

 his studies, of course, to insects. 



I do not think that a single land-bird was seen on the 

 Tortugas, a fact somewhat surprising at first thought, as one 

 would naturally expect that the comparatively short spaces 

 between the various Keys would not serve as an effective 

 barrier to flying creatures.^ The explanation may be found 

 in the newness of these islands on the one hand and, what is 

 probably more potent, the further fact that the gales rarely 

 blow directly from the east so as to carry the birds from the 

 mainland or more easterly Keys to the westward, although a 

 moderate breeze often blows directly from the Marquesas. It 

 is also important to note that there is no migration route down 

 the peninsula of Florida, nearly all of the land-birds taking the 

 route via the Mexican side of the Gulf or else wintering in the 

 southern states. We thus find that no land-birds seem to have 

 established themselves on the Tortugas, although there are a 

 number of familiar species on the Bermuda Islands, which lie 

 about six hundred miles due east of Charleston, South Caro- 

 lina. The explanation in the latter case is thought to be to the 

 effect that the birds are caught while migrating southward 

 along the Atlantic coast, and carried by northwest gales in the 

 direction of the islands. 



Even the sea-birds, although numerous in individuals, were 



1 Agassiz says that the Tortugas are visited by a few land-birds, but does 

 not say what species have been found there. — "Three Cruises of the Blake,'* 

 Vol. I, p. 90. 



