OF SELBORNE. 91 
it says that it sung so like a reed-sparrow that he 
took it for one, and that it sings all night; but this 
account merits farther inquiry. For my part, I 
suspect it isa second sort of locustella, hinted at by 
Dr. Derham in Ray’s Letters (see p. 74). He also 
procured me a grasshopper-lark. 
The question that you put with regard to those 
genera of animals that are peculiar to America, 
viz., How they came there, and whence? is too puz- 
zling 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 plaus- 
ible arguments to support whatever theory they 
shall choose to maintain ; but then the misfortune 
is, every one’s hypothesis is each as good as anoth- 
er’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 | 
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 ma- 
chinery: it is a difficulty worthy of the interposi- 
tion of a god! “ Incredulus odi.” 
TO THOMAS PENNANT, ESQ. 
THE NATURALIST’S SUMMER EVENING WALK. 
“‘ Equidem credo, quia sit divinitus illis 
Ingenium.” VirG., Georg. 
_ Wuen day, declining, sheds a milder gleam, 
_ What time the Mayfly* haunts the pool or stream ; 
* The angler’s Mayfly, the ephemera vulgata, Linn., comes forth 
