252 
EPHEMERA. 
the next day notwithstanding. According to the 
figure given by Swammerdam it is extremely 
allied to the larva of the Ephemera vulgata, resid- 
ing chiefly in tubular cavities which it forms in 
the mud or clay of the waters it inhabits, occa- 
sionally coming out in quest of food. In this re- 
spect it agrees with the larva) of several others of 
this genus, which have a similar habit of forming 
tubular hollows in the banks of their native waters. 
When arrived at full growth the larva or, more 
properly, pupa, rises, like tliat of the common 
Ephemera, to the surface of the water, generally 
between the hours of six and seven in the evening, 
and the skin of the back cracking, and springing 
otf with an elastic motion, the Fly is almost in- 
stantaneously evolved, as in the common species; 
after which it flies to the nearest convenient spot, 
and again divesting itself of its pellicle, appears 
in its perfect or ultimate state. It now flies 
again to the water, and fluttering over its surface, 
as if sporting with its innumerable companions, 
enjoys all tlie pleasures of its short remainder of 
existence: the female breeds, deposits her eggs, 
and, like the male, perishes before, or with the 
dawn of the approaching day. 
'riiis species, according to Swammerdam, is ex- 
tremely frequent in the mouths or entrances of 
the Rhine, the Maes, the Wael, the Leek, and the 
Isel. It appears in the fly or perfect state about 
midsummer, and the season of its appearance 
lasts only three days, none being seen again till 
the following year. 
