ORDER BRANCH IOPODA. 
353 
dilations. At the end of the first moulting, the two compo- 
site eyes appear, the body is elongated posteriorly, and ter- 
minates in a conical articulated tail, with two filaments at the 
end. The following moultings gradually develope the feet, 
and the oars vanish. The sucker, which in the early age 
extends over the belly and covers it, also diminishes in pro- 
portion. 
These branchiopoda are found, and usually in great abund- 
ance, in small pools of fresh and muddy waters, and often in 
those which are formed after great rains, but particularly, as it 
would seem, in spring and autumn. The first frosts cause them 
to perish. They swim with the greatest facility on the back, and 
their feet, incapable of any service in walking, then present an 
lulatoi y movement, very agreeable to witness. This move- 
ment produces a current of water between them, and which, 
going along the canal of the chest, carries to the mouth the 
small corpuscula on which the animal is sustained ; but when 
it is desirous of advancing, it strikes the water quickly with 
its tail, on the right and left, which causes it to proceed, as it 
were, by bounds and leaps. When taken out of this element, 
it moves its tail for some time, and curves itself circularly. If 
deprived of a sufficient quantity of moisture, it makes no fur- 
ther movement. 
According to the report of Benedict Prevost, the male of the 
species, which is the subject of his memoir, when desirous of 
coupling, swims around his female, seizes her by the neck with 
the corniform appendages of his head, and holds himself fixed 
there until she receives the posterior extremity of his tail, so 
as to draw near the two valves of the copulative organs. This 
coupling thus resembles that of the libellulae. The eggs are 
yellowish, spherical at first, and then angular, with a thick 
and hard shell, which contributes to their preservation. It 
even appears that desiccation, unless carried to too great an 
extent, will not injure the germ, and that the young are dis- 
voL. xi n. a. a 
