NEUEOPTEEA. 239 



water and the case is made of little fragments of wood, 

 shell, and sand, agglutinated together so as to float ; the 

 perfect insect is not aquatic, and flies away when formed. 

 The May-flies are noted for the shortness of their 

 existence, the larva? live in the water, and many of 

 them are eaten by fishes who are very fond of them, 

 but sufficient numbers come to the perfect state, to 

 form complete clouds in the air where the larva? were, 

 these creatures live but a day, and some of their species 

 but an hour or two, in the perfect state, they deposit 

 their eggs in the water, which come to life in the mud 

 at the bottom. The flight of these fragile beings and 

 their short-lived holiday festivities are well described 

 by Kirby and Spence : 



" In the beginning of September, for two successive 

 years, I was so fortunate as to witness a spectacle of 

 this kind, which afforded me a more sublime gratification 

 than any work or exhibition of art has power to com- 

 municate. The first was in 1811. Taking an evening 

 walk near my house, when the sun, declining fast 

 towards the horizon, shone forth without a cloud, the 

 whole atmosphere over and near the stream swarmed 

 with infinite myriads of Ephemera? and little gnats of 

 the genus chironomus, which in the sun-beam appeared 

 as numerous and more lucid than the drops of rain, as 

 if the heavens were showering down brilliant gems. 

 Afterwards, in the following year, one Sunday, a little 

 before sunset, I was enjoying a stroll with a friend at a 

 greater distance from the river, when in a field by the 

 road-side the same pleasing scene was renewed, but in a 

 style of still greater magnificence ; for, from some cause 

 in the atmosphere, the insects at a distance looked much 

 larger than they really were. The choral dances consisted 

 principally of Ephemera?, but there were also some chiro- 

 nomi, the former, however, being most conspicuous, at- 

 tracted our chief attention. Alternately rising and fall- 

 ing, in the full beam they appeared so transparent and 

 glorious, that they scarcely resembled anything material; 

 they reminded us of angels and glorified spirits drinking 



