144 NATURAL HISTORY 



in long and tedious voyages. It is from 

 this defect of food that our collections 

 (curious as they are) are defective, and we 

 are deprived of some of the most delicate 

 and lively genera. 



I am, &c. 



LETTER XXXI. 



TO THE SAME. 



DEAR SIR; Sklborne, Sept. 14, 1770. 



You saw, I find, the ring-ousels again 

 among their native crags ; and are farther 

 assured that they continue resident in those 

 cold regions the whole year. From whence 

 then do our ring ousels migrate so regu- 

 larly every September, and make their ap- 

 pearance again, as if in their return, every 

 Jpril ? They are more early this year than 

 common, for some were seen at the usual 

 lull on the fourth of this month. 



