78 
NATURAL HISTORY OF SELBORNE. 
and whence ? is too puzzling for me to answer ; and yet so 
obvious as often to liave 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 v^riters 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 divinitii ill us 
Ingenium. Virg. Georg. 
When day declining sheds a milder gleam, 
What time the may-fly i" 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 vagrant| 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 darkening 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 guides 
* The reader curious on this subject will not consult a better Work than the second voliinie of 
Lyell's Principles of Geology. — Ed. 
t The angler's may-fly, the ephemera 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. — Note. If kept, however, from the other sex, they will survive several days. — Ed. 
t Vagrant cuckoo : so called because, being tied down bj-^ no incubation or attendance about 
the nutrition of its young, it wanders without control. — Note. From long-continued and careful 
observation of the habits of this species, I am inclined to a contrary opinion, and, in fact, can 
no'^ only say decisively that it has a fixed habitation, but have also reason to believe that it returns 
veapv to the same spot, as is the usual custom with the feathered race. — Ed. 
5 Okdicnemus Europaus- 
