THE MAY-FLIES. 193 



A considerable number of British insects agree 

 witb the common May-fly in most of the more im- 

 portant characters^ both of structure and transforma- 

 tion^ above described ; these form the tribe of Ephe- 

 MERiNA_, or May-flies^ of which the distinctive cha- 

 racters may be recapitulated as follows : — the antennse 

 are minute^ tapering^ and composed of three joints ; 

 the eyes are large_, with three ocelli between them ; 

 the wings more or less reticulated^ the anterior pair 

 much larger than the posterior, which are even 

 sometimes entirely deficient (as in the genus Cloeon) ; 

 the abdomen is terminated by two or three jointed 

 filaments, and lastly, the organs of the mouth are 

 rudimentary and quite useless. The legs are slender, 

 and of moderate length, except the anterior legs in 

 the males, which are greatly elongated, and the tarsi 

 are composed of five joints. 



In the structure and mode of life of their larvae 

 and pupse these insects are also very similar, although 

 it appears to be principally the larger species that 

 ensconce themselves, during their preparatory states, 

 in a comfortable habitation hollowed out in the banks 

 of the water they inhabit ; the larvse of the smaller 

 members of the group apparently considering the 

 mud and stones at. the bottom a sufficient protection 

 from the unwelcome attentions of the fishes, with 

 which they are a favourite article of food. The larvse 

 and pupse of these smaller species are also far more 

 active than those of their more bulky relatives, and 

 the pupa of one species of Cloeon is described by Mr. 

 Westwood as moving with astonishing rapidity both 

 backwards and forwards^ leaping in the water to a 

 considerable distance, and swimming by the agency 

 of its gill-plates. They all exhibit the same caudal 



