History of British Fmtomostraca. 319 



covering having grown under the old one, when the process of 

 changing it commences, the insect fastens itself to the bottom or 

 side of the vessel in which it is, or to any solid object near it, so as 

 to give itself support. It then, by moving its limbs, and shaking 

 the valves of the shell, the new parts at the same time coming for- 

 ward, loosens the old covering, and in a short time frees itself from 

 the exuviae altogether, leaving behind, the sheaths of the limbs, 

 hairs, plumes, and even the minute setulae that almost escape the 

 power of the microscope itself from their fineness, such as the de- 

 licate plumose setae which adorn the long filaments of the tail. 

 " How, beyond all idea," says Muller, from whom I have taken this 

 description, " this most subtle fineness, for they are sheaths con- 

 taining other smaller sheaths, which again include other organs 

 smaller still." * The number of times they moult during life is 

 not known, but Jurine says, they ordinarily, though not always, 

 moult before each time of laying eggs. They certainly do not al- 

 ways do so ; and perhaps the frequency of their moulting may de- 

 pend much upon the temperature, the seasons, &c. 



Having the experiments of Spallanzani and others, upon the re- 

 production of mutilated members in various animals, before his 

 eyes, M. Jurine instituted a series of experiments upon the C. qua- 

 dricornw, to see how far this power existed in this genus of insects. 

 In most of his experiments he failed, the insects having died be- 

 fore they moulted, and without showing any evident change in the 

 mutilated members. At length he succeeded. He cut off about 

 two-thirds of an antenna in a female which lived and moulted, re- 

 appearing, after moulting, with a beautiful perfect new antenna, 

 the old one of the cast shell not having shown the least indication 

 of a change.t 



Some authors have asserted that these insects possess a wonder- 

 ful power of resisting drought, and that when, by reason of the 

 summer heats, the marshes become dried up, the little creatures do 

 not die, but as soon as the mud becomes moistened by the rain, they 

 recover entirely. Jurine, however, doubts this, and instituted a 

 series of experiments to prove that they have not this faculty. He 

 selected 1 2 of the C. quadricornis, removed them out of the water, 

 and allowed them to remain fifteen minutes dry ; 7 of them he found 

 to be irrecoverably dead, the remaining 5 recovered. Again he se- 

 lected 12 others, and allowed them to remain twenty minutes dry 



1 1 out of the 12 died. A third time he selected 1 2, and after expos- 



* Entomostvaca, p. 9. f Hist, des Monoc. p. 40. 



