152 Ephemera, the May-Fly. 



occurrence of such countless swarms of Ephemeridae is un- 

 known in the British Isles. 



The term Ephemera, so applicable to this creature of a day, 

 must not be understood in too restricted a sense. It is quite 

 true that numbers are devoured by fish or bird before they 

 assume their final change, and that survivors have but a very 

 brief existence. After the laying of the eggs, which, however, 

 may last more than a single day, the female perishes, or dies a 

 natural death. The only business of her life being accom- 

 plished, she has now only to die. If, however, a specimen be 

 caught, and kept in confinement, and the laying be thus 

 checked, an Ephemera may live several days. Whether the 

 males are as short-lived as the females, I am unable to say ; 

 but I think it not improbable that they may survive somewhat 

 longer, though, from the fact of their taking no food, it is 

 probable that the life of all the Ephemeras is of a very short 

 continuance. 



The family of Ephemeridae consists of several genera, and 

 their study will amply repay the observer. It is almost im- 

 possible to conceive any creatures more exquisite than some of 

 the small kinds belonging to the genera Baetis, Gloe, and Goenis. 

 The genus Ephemera is characterized by having three nearly 

 equal caudal setae in both male and female ; these appendages 

 are longer in the male, which is also readily distinguished from 

 the female by its possessing two curved, clasping organs 

 (Fig. D, a), longer fore-feet and setaceous tail appendages. 

 The colour of the male of Eph. valgata is much darker than 

 that of the female, being bronze or chocolate ; the male is also 

 much smaller. 



There is another species of Ephemera besides E. vulgata, 

 the male of which I have occasionally met with in May and 

 June. It is often, no doubt, mistaken for the female of the 

 E. vulgata, which it much resembles in colour. It may often 

 be seen in companies executing the characteristic dance. It 

 does not agree with the description of E. cognata of Stephens, 

 nor with Pictet's E. danica. There is also a fly known to 

 anglers as the mackerel, a dark brown Ephemera : the colour is 

 said to be the same both in the male and female. I have not 

 been able to ascertain what species it is. 



The eggs, after having been deposited in the water, sink 

 to the bottom, and change into a small larva; in this state it 

 is said to live for two or three years, and then to change to the 

 nympha (Eig. B). Both in its larval and nymphal condition, 

 the creature eats. The intestinal canal contains numerous algae 

 spores, small Crustacea, rotifera, etc. 



The larvae and nymphaa are often found in holes in the 

 river banks, and frequently also in the sand or mud at the 



