[ 2 &6 } 



Calais,, from Gibraltar to Tangier s or any other fucli; 

 narrow (trait, as the oppolite coaft-s are clearly- within ■, 

 the bird's ken, and the palTage is no more adventurous, 

 than aerofs a large frefh water lake. 



I as little mean to deny that there may be a peri- 

 odical flitting of certain birds from one part of a con- 

 tinent to another : the Royfton Crow, and Rock- 

 Ouzel, furnifh inftances of fetch a regular mi- 



gration. 



What I mean chiefly to contend therefore is, that: 

 it feems to be highly improbable, birds mould, at: 

 certain feafons, traverfe large tracts of fea,. or rather 

 ocean, without leaving any of the fame fpecies be- 

 hind, but the fick or wounded. 



As this litigated point can only receive a fatisfactory 

 deciiion from very accurate obfervations, all preceding 

 naturalifls, from Ariftotle to Ray, have fpoken with; 

 much doubt concerning it.. 



Soon after the appearance of MOnf.. Adanfon's 

 voyage to Senegal, however, Mr. Collinfon firfr, in 

 the Philolbphical TranfacYions *, and after him the 

 moft eminent ornithologies of Europe, feem to 

 have conlidered this traveller's having caught four 

 European Swallows on the 6th of October,, not 

 far from the African coaft, as a, decifive proof,, 

 that the common fwallows, when they difappeat 

 in Europe, make for Africa during the winter, and 

 return again to us in the fpring; 



It is therefore highly incumbent upon me, who 

 profefs that I am by no means fatisfled with the ac~ 

 count, given by Monf. Adanfon of thefe European 



* Part U. 1760, p. 459', & feq. 



fvvallows> 



