XEUROPTERA. 61 



canal, is almost always full of air-bubbles ; I catcb one 

 of those dancing males, which I recognize by his very 

 long fore-legs, exte-nded so that one might at first sight 

 mistake them for antennjB ; I press him quickly in the 

 middle ; crack he goes 1 for the air-bubbles have burst 

 by the pressure. No wonder that Ephemera's stomach 

 is empty, for, as a fact, he has no real mouth ; there is 

 no passage from the mouth to the stomach. But though 

 the stomach is full of air, we must not suppose that 

 Ephemera suffers at all from flatulence. The air in the 

 intestinal canal, there can be no doubt, serves the pur- 

 pose of a balloon and helps to buoy the insect up, and 

 saves the expenditure of muscular force ; for as no food 

 is taken to supply the waste, the muscles are not capable 

 of long-sustained action. 



The peculiar up-and-down flight of the May-flies 

 must be familiar to everyone. In groups they love to 

 practice their up-and-down flight ; with head erect and 

 bodies prettily curving upwards they exerci'se their 

 characteristic dance, especially when the sun shines 

 brightly and the air is still. But I must here notice 

 that it is the males that exercise this particular style of 

 dance, rising up sometimes ten or twelve feet, then 

 dropping down again suddenly the same distance ; at 

 least I think this dance, as a rule, is strictly confined 

 to the gentlemen, for 1 have never detected a lady 

 May-fly in her marbled dress of white and brown 

 amongst the company. 



I should mention that the "Green-drake" of the 

 Fly-fisher is the sub-imago stage of the May-fly, while 

 the " Grey-drake" is the perfect imago female. It is in 

 their sub-imago state that so many thousands fall 



