o:f selborne. 179 
When brown owls hoot, their throats swell as big as a 
hen^s e^^. I have known an owl of this species live a full 
year without any water. Perhaps the case may be the 
same with all birds of prey. When owls fly they stretch 
out their legs behind them as a balance to their large heavy 
heads : for as most nocturnal birds have large eyes and 
ears they must have large heads to contain them. Large 
eyes I presume are necessary to collect every ray of light, 
and large concave ears to command the smallest degree of 
sound or noise. 
It will be proper to premise here that the sixteenth, eighteenth, 
twentieth, and twenty-first letters have been published already in the 
" Philosophical Transactions :" but as nicer observation has furnished 
several corrections and additions, it is hoped that the re-publication of 
them wiU not give oiFence ; especially as these sheets would be verj 
imperfect without them, and as they will be new to many readers who 
had no opportunity of seeing them when they made their first appear- 
ance. — G. W. 
The Hirundines are a most inoffeusive, harmless, enter- 
taining, social, and useful tribe of birds : they touch no 
fruit in our gardens ; delight, all except one species, in 
attaching themselves to our houses ; amuse us with their 
migrations, songs, and marvellous agility : and clear our 
outlets from the annoyances of gnats and other troublesome 
insects. Some districts in the South Seas, near Guayaquil,^ 
are desolated, it seems, by the infinite swarms of venomous 
mosquitoes, which fill the air, and render those coasts in- 
supportable. It would be worth inquiring whether any 
a large number of beetles belonging to seven or eight different genera, 
besides quantities of cock-chafers {Melolontha vulgaris). In pellets 
of the long-eared owl, he found remains of mice 14, voles 271, shrews 
2, and small birds 3. Of the short-eared owl he examined only a few 
pellets, which were found to contain the remains of water voles only, 
but as these were obtained in a single locality where these animals were 
especially abundant, he reserved his remarks on the food of this owl 
until he could make further investigati«>ns. In the details, however, 
which he has furnished, we have abundant proof of the important ser- 
vices which owls render to the agriculturist. — Ed. 
1 See " Ulloa's Travels."— G. W. 
