ORDER BRANCHIOPODA. 
337 
According to the Genevese naturalist just cited, these ani- 
mals, when they swim, move the two anterior feet with as much 
rapidity as the antennae ; but they move them slowly when 
they walk on the surface of marshy plants. These feet, con- 
jointly with the two terminated by a long hook, or the penul- 
timate feet, then support the body. He supposes that those 
which, according to him, form the second pair, are intended 
to produce an aqueous current, and direct it towards the 
mouth. This would assimilate their functions to those of the 
lower antennae, which he names antennulae. The two fila- 
ments composing the tail are united, and seem to form but 
one, when they come forth from the testa. They answer the 
purpose, as is presumed, of cleansing its interior. The female 
deposits her eggs in a mass, fixing them, by means of a gluten, 
on plants or mud. Hooked, at this time, with the aid of the 
second feet, and so as not to fear the shocks of the water, she 
employs almost twelve hours in this operation, which in the 
larger species furnishes as many as four and twenty eggs. 
M. Jurine has collected some of these packets of eggs, when 
they came forth, and after having isolated them, he has seen 
them disclose the young, and he has obtained another gene- 
ration without the intervention of the males. A female which 
had laid its eggs on the twelfth of April, up to the eighteenth 
of May inclusive, changed skin six times. The twenty-seventh 
of the same month she laid a second set, and two days after, 
on the twenty-ninth, a third. He concludes from this, that 
the number of moul tings from infancy is in relation with the 
gradual development of the individual ; that this development 
cannot manifest itself but by the general separation of an 
envelope become too small to lodge the animal ; and that 
there is a determinate limit of size to which the latter must 
attain. 
The lophyropa of our third division, (our Cladocera) or the 
Daplinides of M. Straus, compose, in the history of the mono- 
VOL. XIII. 
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