424 CLASS VIIL 



SWAMMERDAM, in the species described by him, did not observe 

 the copulation, and supposes that the eggs, as in fishes, are first laid, 

 and afterwards fertilised by the male. REAUMUR doubted this, 

 because the eggs sink in water. But R(ESEL, DE GEER, and later 

 writers, have actually observed the copulation in other species; 

 and thus it is improbable that the species of SWAMMERDAM forms 

 an exception on this point. 



Ephemerce 011 the whole live as perfect insects but a short time, 

 some not even a single day. Once however I kept some specimens 

 of Ephemera diptera (Cloe diptera PJCTET) for some days alive under 

 a glass, two for more than a week. 



" Ephemera) larvce natant in aquis ; volatiles facto? fruuntur 

 gaudio, uno scepe eodemque die nuptias, puerperia et exsequias 

 celebrantes" Lnraraus, Syst, natur. i. ed. xn. p. 906. 



Comp. on this family : 



Ephemeri vita of Afbeeldingh van's menschen leven door J. SWAMMERDAM. 

 Amsterdam, 1675 kl. 8vo. m. afb. (For the facts see Bijbel der natuur, I. 

 bl. 234 270, Tab. xin xv.) 



K^AUMUB, Mem. p. servir a I'lfist. des Ins. vi. pp. 457522 ; DE GEEB, 

 Mem. n. pp. 617660. PI. 1 6 1 8. 



F. J. PICTET, Hist. not. des Insectes Nevroptdres, Seconde Monographic, 

 Famitte des EpMmerines. G-eneve, 1843. 8vo. avec pi. 



A. Wings with transverse nervuresfew, posterior often obsolete. 



1) Compound eyes two both in males and females. 



Sub-genera : Oligoneuria PICTET (Wings four), Ccenis STEPHENS, 

 PICTET (Wings two). 



2) Eyes four in males; the two accessory large, petiolate. 



Sub-genus Cloe LEACH, BURM., PICTET. Posterior wings very 

 small or obsolete. Caudal setae two. 



B. Wings fowr, with transverse nervures numerous. 



1) Two accessory eyes in males, as in the preceding genus. 



Sub-genus : Potamantlius PICTET. Caudal setae three. 



2) Compound eyes only two in both sexes. 



Sub-genus : Bcetis LEACH, PICTET. Caudal setaa two. 



Sub-genera : Ephemera, Palingenia BURM., PICTET. Caudal setae 

 in females three, in males the intermediate one sometimes shorter or 

 abortive. 



