302 NATURAL HISTORY OF AQUATIC INSECTS CH. 



" When the winged fly has become completely free, 

 it again seeks the water, and floats upon the surface | 

 from time to time, as if in sport. Now and then it | 

 rests upon the water with the help of its long tail- 

 filaments, the wings being folded together. The 

 hairs, with which the tail-filaments are so abundantly 

 provided, prevent the Insect from sinking. The same 

 may be observed in other Insects, like the larva of 

 the Gnat, which employ their hairs and the air 

 entangled in them, to float upon the surface. I 

 believe, but am not certain, that while the male 

 Palingenia during transformation moults twice, the 

 female moults once only.^ The male may be dis- 

 tinguished by the larger size of the eyes, which are 

 twice as great as in the female. The tail-filaments 

 of the female are shorter by a third than those of the 

 male. The colour of the male is more ruddy than 

 that of the female. Lastly, the male, in addition to 

 the two long tail-filaments, has four minute appen- 

 dages, which can hardly be made out in the female. 



" The female deposits her eggs upon the surface of 

 the water, where they are fertilized by the male, as in 

 the case of Fishes.^ 



" In the adult condition these Insects do not eat, as is 

 the case with various other Insects also. The mouth- 

 parts and alimentary canal of the winged fly are 

 completely useless and empty. Hence the lightness 



^ That is, the female remains in the subimaginal skin, or 

 transparent covering described above, while this is cast by the 

 male. This statement is not confirmed by observation of other 

 EphemercC. 



- This is a mistake, as mentioned above- 



