58 
KEUROPTERA. 
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genera Baetis, Chloe, and Coenis, are exquisitely 
beautiful and delicate in form. 
The genus Ephemera is characterized by the posses¬ 
sion of three nearly equal hair-like appendages at the 
end of the tail; they are longer in the male insect, 
which is further distinguished by two curved clasping 
organs at the end of the abdomen. The May-fly 
deposits her eggs by little packets at a time, first in one 
place, now in another, in the water; they soon sink 
and become attached to submerged weeds and stones ; 
soon they change into larvrn, very curious creatures 
indeed; in their larval stage they are believed to live 
for two or three years, during the whole period of which 
they are active eaters. I have found the intestinal 
canal of the larva to contain the spores of numerous 
algse, small Crustacea, rotifera, etc. Both lame and 
nymphoe are often found in holes in river banks, and 
frequently in the sand or mud at the bottom of the 
water. The only difference between larva and nyinpha 
is that the latter has sheaths for the wings, which are 
rolled or crumpled up inside. The banks of rivers may 
often be seen to be riddled by these larvae, which tunnel 
for themselves tubular galleries in the mud to the depth 
of four and five inches. The larvm of some other 
members of the May-fly family, instead of living in 
sand or in tubular galleries, swim from place to place, 
resting on the leaves and stems of water plants. The 
abdomen of the larva and nympha of Ephemera vulgata 
is bordered on either side by a row of gills, which, by 
their constant motion, serve to draw fresh currents of 
water to oxygenate the blood. Each gill consists of two 
large trachial trunks, in which small air vessels ramify in 
