68 
NATURAL ^^ IS TORY 
on that fubjed little fatisfadtlon is to be found. Ingenious men. 
will readily advance plaufiblc arguments to fupport whatever 
theory they fhall chufe to maintain; but then the misfortune is, 
every one's hypothefis is each as good as another's, fmce they are 
all founded on conjefture. The late writers of this fort, in whom 
may be feen all the arguments of thofe that have gone before, as I 
remember, ftock America from the weftern coaft of Africa and the 
fouth of Europe ; and then break down the Ifthmus that bridged, 
over the Atlantic. But this is making ufe of a violent piece of 
machinery: it is a difficulty worthy of the interpofition of a god ! 
*' here dull', s odi". 
TO THOMAS PENNANT, ESQJTIRE. 
THE NATURALIST'S SUMMER-EVENING WALK, 
equidem credo, quia fit diviiiitus illis 
Ligcnium. Virg. GEORGt 
w HEN day declining fheds a milder gleam. 
What time the may-fly'^ haunts the pool or ftream; 
When the ftill owl fkims round the graffy mead. 
What time the timorous hare limps forth to feed ;. 
d The angler's may-fly, the ef beniet-a njulgata Linn, comes fortJi from it's aurelia 
ftate, and emerges out of the water about fix in the evening, and dies about eleven at 
night, determining the date of it's fly ilate in about five or fix hours. They ufi-ially be- 
gin to appear about the 4th of June, and continue in fucceflion for near a fortnight. 
See Svjat/imerdam, Derliam, Scopoli, £ft. 
Then 
