THE DAY FLY. 
476 
males impregnated, and tlie eggs dcpofited ; and tliefe 
funftions are no fooner over, than the active beings who 
performed them finidi tiieir operations for ever *. 
On the banks of tbe Sicne and the Marne, in the vici- 
nity of Paris, the ephemerae exhibit a lingular fpe&acle 
for fome days about the middle of Augujl. For feveral 
Fours after funfet, they rife in fuch vail multitudes, that 
they appear like the flakes prefling upon each other in a 
heavy fall of fnow. By and by, the whole furface of 
the earth is covered with the fwarms that have lallen 
upon it, after having fitiiflied their lliort exiftence. 
The chryfalids that remain under the water begin their 
transformation in the evening, and complete it by eight 
or nine o’clock ; an operation painful and difficult to 
other infefts, is with them performed with great celerity 
and apparent eafe. No fooner has the chryfalis reached 
the top of the water, than its prifon burfts open, and the 
winged ephemera foars into the air. Millions alter mil- 
lions are thus conllantly taking wing, till the air becomes 
darkened with their numbers: They are in that element 
but an inflant, when abundant fliowers of them fall back 
to the ground. 
The females, after their fall, are bufy in performing 
tbe laft fun&ion of their lives, which is, depofiting their 
eggs. Such as have dropped upon the ground leave them 
there ; while thofe that have tumbled into the river pro- 
duce two feparate cluflefs of ova, each containing no lefs 
than three hundred anti fifty. All this is the work only 
pf a moment ; for other infe&s are not fooner delivered 
pf a fingle egg, than file ephemera of feven hundred. 
Some 
2 
♦ ^eauthur, Tome VI. p. 44. Pref. 
