34 best's art of angling. 



three-haired tail^ behind on the case. After it 

 has reposed itself a while, it flies with great 

 briskness to seek its mate. In the new fly a 

 remarkable difference is seen in their sexes, 

 which I could not so easily perceive in their first 

 state, the male and female being then much of 

 a size; but now the male was much the smallest, 

 and the hairs in his tail much the longest. I was 

 very careful to see if I could find them engen- 

 dering, but all that I could discover, was, that 

 the males separated, and kept mider cover of 

 the trees, remote from the river; hither the fe- 

 males resoried, and mixed with them in their 

 flight, great numbers together, with a very brisk 

 motion of darting or striking at one another 

 when they met, with great vigor, just as house- 

 flies will do in a sunny-room : this rhey conti- 

 nued to do for many hours, and this seemed to 

 be their way of coition ; which must be quick 

 and soon performed, as they are of so short a 

 duration. When the females were impregnated, 

 they left the company of the males, and sought 

 the river, and kept constantly playing up and 

 down on the water. It was very plainly seen, 

 that every time they darted down they ejected a 

 cluster of eggs, which seemed a pale bluish speck, 

 like a small drop of milk, as they descended on 

 the water ; then, by the help of their tail they 

 spring up again, and descend again, and thus 

 continue until they have exhausted their stock 

 of eggs, and spent their strength, being so weak 

 that they can rise no more, but fall a pre}'' to the 

 fish ; but by much the greater number perish on 

 the waters, which are covered with them : this 

 is the end of the females; but the males never 

 resort to the rivers, as I could perceive, but after 

 they have done their office, drop down, languish 



