294 NATURAL HISTORY OF AQUATIC INSECTS CH. 



brown, and the back speckled with dark spots, which 

 become larger with age. 



" The male larvae are distinguished in the first 

 place by the eyes, which are twice as large as in the 

 female. The body of the male, however, is much 

 smaller than that of the female, as in all other Insects 

 which I have observed. 1 The effect of this difference 

 in size, is that space is allowed for the vast number 

 of eggs formed in the female. The male has longer 

 tail filaments, and possesses moreover three or four 

 appendages, placed partly on the sides and partly 

 beneath, which in the female are inconspicuous or 

 wanting altogether. 



" The larva is harmless and inoffensive. If roughly 

 handled, it bends its head towards the breast, and 

 stiffens its body. There is nothing more wonderful 

 in these creatures than the play of the branchiae 

 which stand out from both sides of the body. They 

 move so regularly, distinctly, and incessantly, as to 

 excite admiration in the beholder. 



" I come next to consider the transformation of 

 this Insect. The change is effected so rapidly that it 

 seems to consist merely in slipping off two integu- 

 ments and unfolding certain appendages. In order 

 to make it quite plain what is the difference between 

 the swimming larva and the flying Insect, I will first 

 describe the internal organs as they occur in both 

 stages. Here I follow a path trodden by no one 



1 Since Swammerdam's time a good many exceptions to this 

 rule have been noted, among the rest, the Stag-beetle, Dynastes, 

 Megasoma, many Dragon-flies, the Honey-bee and other Bees, 

 Methoca, c. See Darwin's Descent of Man, chap. X. 



