EPHEMERA. 253 
According* to Swammerdam’s figure the size of 
the animal is at least equal to that of the Ephe- 
mera vulgata, from which it principally differs in 
being of a white colour, and in having but two 
caudal bristles, though in its larva state it was 
furnished with three. 
Among the smaller Ephemerae the species are 
by no means easily distinguishable, and a degree 
of confusion seems to prevail in their synonyms 
as given by Linnaeus and others. 
Among these smaller species the Ephemera 
halter ata of Linnaeus may be considered as one 
of the most elegant : it is of a white colour, with 
the lower part of the body black: the lower wings 
are so very small as rather to resemble a mere 
pair of small membranaceous processes than real 
wings. It is not uncommon during the summer 
months. The stemmata or false eyes are in this 
species remarkably conspicuous, and are of a flat- 
tened surface : the tail is terminated by three long 
bristles. 
Ephemera diptera of Linnaeus is a somewhat 
larger species than that just mentioned, and has, 
as the name imports, only two wings, no traces of 
lower wings being discoverable. The body is 
brownish, and the wings white, with a strong 
anterior rib or border of yellow-brown, varied by 
cinereous spots. 
