THE EPHEMERID®, OR MAY-FLIES. 5 

British Ephemeride. 
Genus. Species. 
PH EME RAR aa here eae pene cies 3 
LEPTOPHUEBTAGR ss eee 4 4 wings and 
POTAMAN TELUS sare: 2 aonenve I 3 tails. 
EPH E MERE AGIAN eee cies gue I 
BAH TIS pase rsee ee ee sat heen eee 9 
EEG PE ANCIINGUA: sieeehecs ore naiet cee 8 4 wings and 
CENLER@P TamWIM cron ates 2 2 tails. 
OL Piss RaU Ss Lone ne done cnet eee 2 
CANIS 2 wings and 
FRE cs aia Raho 4 toile 
CLOEON 2 wings and 
PN ne hc UR sR 4 Bie 
In ascertaining the genus to which any specimen belongs, note 
the following peculiarities : the presence or absence of hind wings 
and middle tail, (the female may have the middle tail when it is 
absent in the male); the nature of the neuration of the large 
wings, whether the longitudinal nervures are many and complex, 
or few and simple; whether the transverse nervures are numerous 
or not, especially in the costal and sub-costal areas ; whether the 
interneural veinlets of the terminal margin, if present, are con- 
tinuous with the longitudinal or with the transverse nervures, or 
are separate from both, and, if separate, are they single or in pairs ? 
The general character of the neuration only need be considered, 
not particular details. The wings of Ephemera and Cloéon 
illustrate some of these peculiarities. ‘The hind wings may be 
small, as in Ephemera, or mere rudiments, as in Baetis and 
Centroptilum. Next examine the tarsi, to ascertain whether there 
is a fifth joint, and the relative proportions of the joints, and the 
form of the claws. Note the comparative length of the tarsi, 
tibia, and femora in both sexes; in what respect the compound 
eyes of the male differ from those of the female; the form and 
number of joints of the male forceps, usually three or four, but in 
some genera only two, and in Cezenis jointless. 
Another item of importance is the attitude assumed by the 
subimago during repose. ‘The forelegs may be elevated or on the 
ground, held together or separated; the tails may be nearly parallel 
or spread out; the wings may be elevated or depressed. ‘The 
subimago state may last for some hours, or be quitted immediately, 
or be the permanent state of the female. 
The characteristics of the nymph must be considered. ‘The 
head may be armed, to enable it to form burrows in the mud, 

