ORDER BRANCHIOPODA. 331 



sent strangulations and a swelling, followed by a hinge-joint. 

 By means of these organs, or of one of them, they seize either 

 the last feet or the end of the tail of their females, in their 

 amorous preludes, and retain them in spite of themselves • 

 in situations appropriate to the manner in which they 

 fix themselves. The females carry off the males when they 

 do not at first wish to yield to their desires. Intercourse takes 

 place as in the preceding Crustacea by prompt and reiterated 

 acts. Jurine has witnessed three in the space of a quarter of 

 an hour. It was believed until his time that the generative 

 organs of the males were situated at the upper antennae; and 

 this erroneous opinion appeared to receive some confirmation 

 from analogous facts observed in the araneides. On each side 

 of the tail of the females is an oval sac, filled with eggs (exter- 

 nal ovaiy, Jurine), adhering by a very slender pedicle to the 

 second segment, near its junction with the third, and where 

 also the orifice of the deferential canal of the eggs is visible. 

 The pellicle forming these sacs is but a continuation of that 

 of the internal ovary. The number of the eggs which they 

 contain augments with age. At first, brown or obscure, they 

 afterwards assume a reddish tint, and become almost trans- 

 parent when the little ones are ready to come forth, but with- 

 out growing larger. If they are isolated or detached, at least 

 at a certain period, the germ will perish. A single fecunda- 

 tion (but that is indispensable) may suffice for successive gene- 

 rations. The same female can have ten broods of eggs in the 

 space of three months. Counting but eight, and supposing 

 each of them to consist of forty young, the sum total of births 

 would amount to nearly four thousand five hundred millions. 

 The duration of the stay of the foetus in the ovary is from two 

 to ten days, which depends on the temperature of the seasons, 

 and divers other circumstances. The oviferous sacs some- 

 times present elongated glandiform bodies, more or less nume- 

 rous, which appear to be assemblages of infusory animalcules. 



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