424 CLASS VIII. 
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. R&aumMuR doubted this, 
because the eggs sink in water. But Rasrr, De Gus, 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. 
Ephemere on 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 (Cloé diptera Picrer) for some days alive under 
a glass, two for more than a week. 
“ Ephemerw larve natant in aquis; volatiles facte frwuntur 
gaudio, uno sepe eodemque die nuptias, puerperia et exsequias 
celebrantes.” Linnazus, Syst. natur. 1. ed. x11. 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 Bybel der natuur, I. 
bl. 234—270, Tab. X11I—XvV.) 
Réaumur, Mém. p. servir a UHist. des Ins. Vi. pp. 457—522; DE GEER, 
Mém. i. pp. 617—660. Pl. 16—18. 
F. J. Prorer, Hist. nat. des Insectes Névropteres, Seconde Monographie, 
Famille des Ephémerines. Gendve, 1843. 8vo. avec pl. 
A. Wings with transverse nervures few, posterior often obsolete. 
1) Compound eyes two both in males and females. 
Sub-genera : Oligonewria Pictnt (Wings four), Cenis STEPHENS, 
Picter (Wings two). 
2) yes four in males; the two accessory large, petiolate. 
Sub-genus Cloé Leacu, Burm., Picrer. Posterior wings very 
small or obsolete. Caudal setze two. 
B. Wings four, with transverse nervures numerous. 
1) Two accessory eyes in males, as in the preceding genus. 
Sub-genus : Potamanthus Picrer. Caudal sete three. 
2) Compound eyes only two in both sexes. 
Sub-genus: Betis Leacu, Picrer. Caudal sete two. 
Sub-genera: Hphemera, Palingenia Burm., Picret. Caudal sete 
in females three, in males the intermediate one sometimes shorter or 
abortive. 
