78 METAMOKPHOSES OP MAN 



the 8th to the 18th. of August. The skin of the 

 animal bursts very soon after, and the perfect insect 

 throws off its envelope as easily as we would throw 

 off a coat. It now flies away, leaving its gills, which 

 have been replaced by stigmata, and its chewing 

 apparatus, which it no longer requires, attached to 

 the cast-off skin. Gradually the number of winged 

 ephemera increases ; about nine o' clock they fill the 

 whole air; from this till about half-past nine they 

 form perfect clouds, enshrouding the observer, and, 

 falling upon him, and the ground, and water, like a 

 heavy snow-shower, constitute heaps which are some- 

 times many inches thick. At ten o'clock there are 

 only a few isolated specimens to be seen. In the 

 space of a single hour these insects, which lived for 

 two years under water, have been metamorphosed 

 into air-breathing animals, with finely reticulated 

 wings ; have exercised their amatory passions in the 

 atmosphere ; have deposited masses of from seven to 

 eight hundred eggs ; and finally have ceased to exist, — 

 deserving the epithet ephemeral in its modern sense, 

 far more justly than their Hypanian brethren. 



In the group we have just been examining, the 

 metamorphoses are rather indistinctly marked. The 

 organization of the ephemeron does not differ very 

 widely from that of its larva. Moreover, the pupa is 

 almost a fac- simile of the larva, leads quite as active a 

 life, and, like the latter, inhabits the water also. The 

 white ants and dragon-flies are pretty similar in these 

 respects; in all, however, but especially among the 

 ephemera, we find that the perfect insect corresponds 

 to the ideal type. We shall see that this is sometimes 

 unrepresented, and that in occasional instances the 



