RELATIONSHIP OE THE FAUNA. 95 



In summarizing the general features of the Bermudian 

 fauna as they have been passed in review in the preceding 

 pages the following broad conclusions and facts present them- 

 selves : 



1. The Bermudian fauna is essentially a wind-drift and cur- 

 rent-drift fauna, whose elements have been recei^'ed in prin- 

 cipal part from the United States and the West Indies. The 

 aquatic animals are overwhelmingly Antillean in character, 

 while the animals of the air — birds and insects — are as over- 

 whelmingly North American. 



2. Some portion of the fauna appears to have been derived 

 (through the agency of the return Atlantic current) from the 

 west coast of Eurafrica (including the African Islands), or e^■en 

 from the Azores, while probably but few forms, if any, were 

 given to those regions by the Bermudas. 



3. The large proportion of peculiar forms among the terres- 

 trial Mollusca more particularly, and somewhat less soamongthe 

 arachnids and echinoderms, renders it probable that this fauna 

 is in part of considerable antiquity, and that some of its ele- 

 ments have been developed from a fauna pre-existent in 

 the region when the present physical conditions had not yet 

 been established. This conclusion is supported by the fact 

 that the predecessor of a group of Pulmonata now peculiar to 

 the islands is found fossil or sub-fossil in the rock of these 

 islands. 



4. Certain marked elements of the Bermudian fauna are of 

 a distinctively Pacific type — Mollusca, Crustacea — but it seems 

 impossible at the present time to explain this mixed relation- 

 ship. 



5. The currental water which separates the United States 

 from the Bermudas proves a practically insuperable barrier to 

 the direct passage of marine animals from the one region to 



