474 
THE DAY FLY. 
Genus II. — Ephemera. The Hay Fly. 
The mouth of this genus has neither teeth nor palpi j 
the infefts which compofe it have two, fometimes three 
ftemmata, fituated above the eyes, and larger than is 
ufual in other infects. ' TJie wings, when the animal is 
at reft, (land erect, che upper much larger than the infe- 
rior pair ; the tail is furniihed with an indefinite number 
of fetaceous append'ces f. 
The infedts of this genus have been denominated ephe- 
merae, or diy flies, from the :hortnefs of their lives ; but 
the life of a day is in proportion to that of feveral ani- 
mals of this clufs, what the lives of the antedeluvian pa- 
triarchs were to ours The period allotted by nature for 
the exiftence of certain ephemerae is only a few hours ; 
of fome, even lefs than an hour. To fome infedts, in- 
deed, that bear the generic characters of ephemerae, fhe 
has been more indulgent ; for tliefe are deftined to fee 
more than one revolution of the fun % 
All the day flies are produced from hexapodal worms, 
which are afterwards transformed into chryfalids, of a 
form nearly refenabling their own ; like the parent worm, 
they walk on the fame number of legs. Both the worm 
and the chryfalis are aquatic, and are provided with gills 
like 
* Syft, Nat. p, 9*6. 
| Reaumur, Tome VI. p. 13 . 
