ORDER BllANCHIOPODA. 353 



culations. 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 

 undulatory 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 sufiicient quantity of moisture, it makes no fur- 

 ther movement. 



According to the reportof 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 libellulas. 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. XIII. A a 



