78 NATURAL HISTORY OF SELBORNE. 



and whence ? is too puzzling for me to answer ; and yet so 

 obvious as often to have struck me with wonder. If one looks 

 into the writers on that subject little satisfaction is to be found. 

 Ingenious men will readily advance plausible arguments to sup- 

 port whatever theory they shall choose to maintain ; but then the 

 misfortune is, everyone's hypothesis is each as good as another's, 

 since they are all founded on conjecture. The late writers of 

 this sort, in whom may be seen all the arguments of those that 

 have gone before, as I remember, stock America from the western 

 coast of Africa and the south of Europe ; and then break down 

 the isthmus that bridged over the Atlantic. But this is making 

 use of a violent piece of machinery : it is a difficulty worthy the 

 interposition of a god ! " Incredulus odi."* 



TO THOMAS PENNANT, ESQUIRE, 

 THE NATURALIST'S SUMMER-EVENING WALK. 



equidem credo, quia sit divinitu illus 



Ingenium. VIRG. GEOUG. 



WHEN day declining sheds a milder gleam, 



What time the may-fly f haunts the pool, or stream; 



When the still owl skims round the grassy mead, 



What time the timorous hare limps forth to feed ; 



Then be the time to steal adown the vale, 



And listen to the vagrantj cuckoo's tale ; 



To hear the clamorous curlew call his mate, 



Or the soft quail his tender pain relate ; 



To see the swallow sweep the dark'ning plain 



Belated, to support her infant train ; 



To mark the swift in rapid giddy ring 



Dash round the steeple, unsubdu'd of wing : 



Amusive birds ! say where your hid retreat 



When the frost rages and the tempests beat; 



Whence your return, by such nice instinct led, 



When spring, soft season, lifts her bloomy head ? 



Such baffled searches mock man's prying pride, 



The GOD of NATURE is your secret guide. 



* The reader curious on this subject will not consult a better work than the second volume of 

 Lyell's Principles of Geology- ED. 



t The angler's may-fly, the ephemeta vulgata LINN, comes forth from its aurelia stote, and 

 emerges out of the water about six in the evening, and dies about eleven at night, determining 

 the date of its fly state in about five or six hours. They usually begin to appear about the 4th 

 of June, and continue in succession for near a fortnight. See Swammerdam, Derham, Scopoli, 

 &c. NOTB. if kept, however, from the other sex, they will survive several days. ED. 



t Vagrant cuckoo : so called because, being tied down by no incubation or attendance about 

 the nutrition of its young, it wanders without control. NOTK. From long-continued and careful 

 observation of the habits of this species, I am inclined to a contrary opinion, and, in fact, can 

 not only say decisively that it has a fixed habitation, but have also reason to believe that it returns 

 yearly to the same spot, as is the usual custom with the feathered race. ED. 

 $ (Edicnemus Europoeus- 



