[ 2 42 ] 



for a long flight than any of the fwallow-tribe, and yet it is the 

 latefl comer, and difappears the earlieft of this whole genus f r 

 long before the infects on which it feeds are wanting. 



But this is not all. When this bird is firft feen in the fpring it 

 is all over of a gloffy dark foot colour (except their chins, which 

 are white) ; but by being for a considerable time in the fun and 

 air, they become weather-beaten and bleached before they dif- 

 appear 6 ? 



Now would not this alteration in the colour be occafioned by their 

 pafl'age over the Atlantic, and do we not know that the quicker 

 the motion is, and the longer continued without intermiflion, 

 the more our own Ikins and hair are changed ; and are we not to 

 fuppofe that the fame effects will be produced on the feathersa nd 

 hairs of other animals ? 



I will now beg leave to {rate another objection to the migra- 

 tion of fwallows from Europe to Africa, which is, that if this 

 conjecture is true, the fame thing muft hold with regard to the 

 Northern and Southern parts of Aria. On the contrary, I am in- 

 formed, that fwallows hide themfelves in the banks of the Ganges 

 during what are called the winter months in that part of the 

 world. Du Tertre likewife mentions, that the few fwallows^ 

 feen in the Caribbee Iflands are only obferved in the fummer, as 

 in France. 



Now we are alfured, by Dr. Pallas, that they have not only 

 fwallows in Ruffia and Siberia, but that on the banks of the Okka^, 

 which empties itfelf into the Wolga, in N. Lat. 57, on froft 

 taking place about the 4th of Auguft, they difappeared for that 

 year h . 



f Viz. At the latter end of April a'nd Auguft, Phil. Tranf. vol. LXV. 

 p. 264, et feq. 



s Phil. Tranf. vol. LXV. p. 269. 



h Pallas's Account of his Travels through Ruffia, 



1 Thefe 



