474 '^^^ ^^^ ^^^» 



Genus II. — Ephemera. T"he Day Fiy* 



J. HE mouth of this genus has neitKer teeth nor palpi j 

 the infedls which compofe it have two, fometimes three 

 llemmata, fituated above thfe eyes, and largei than is 

 ufual in other intecls. The wings, when the animal is 

 at reft, ftand eredt, the upper niuch larger than the infe- 

 rior pair ; the tail is furnilhed with an indefinite number 

 of fetaceous appendices f . 



The infecls of this genus have been denominated ephe- 

 merae, or day flies, from the (bortnefs of their lives ; but 

 the life of a day is in proportion to that of feveral ani- 

 mals of this clafs, what the lives of the antedeluvian pa- 

 triarchs v/ere 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 infe£ts, in- 

 deed, that bear the generic chara£lers oT ephemerae, (he 

 has been more indulgent ; for thefe are deftined to fee 

 more than one revolution of the fun t- 



All the day flies are produced from hexapodal worms, 

 which are afterwards transformed into chryfalids, of a 

 form nearly refembling 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 gill* 



like 



I i^!^, N.it. p. peC. f Reaumur, Tome VI. p. IZ» 



