404 History of British Entomostraca. 



its ravenous disposition are defenceless,. so are they the sport of their 

 conqueror ; the few moments of intermission its craving appetite 

 grants them, is occupied equally in the spoil, first pressing them to 

 death, and then tossing them undevoured into the fluid. But should 

 a more powerful insect oppose him, he immediately contracts his 

 parts, and nothing more than the external covering is open to his 

 antagonist's violence, and he will sooner die ignobly than offer the 

 least opposition." * Latreille, in his " Hist, gener. et partic. des 

 Crust, et Insectes," 1802, gives all Muller's species, retaining his 

 names ; and they are given in the same manner by Bosc in his 

 " Hist. Nat. des Crustac. edit, de Buffon par Deterville," 1802 ; 

 both authors giving a number of general details with regard to the 

 genus. Ramdohr in 1805, published a detailed account of the ana- 

 tomy of two species, the D. sima and longispina of Muller, in his 

 " Beytrage zur Naturgeschicte einigen deutschenMonoculus-arten." 

 Previous to his time, Schoeffer, De Geer. and Muller, were the only 

 authors who had attempted any particular anatomical details, and 

 this memoir of Ramdohr added much to what they had already done. 

 Lamarck, in his " Hist. Nat. des Animaux sans vertebres," 1818, 

 gives two species from Muller ; and Samouelle, in his " Hist, of 

 British Insects," 1819, gives one. In " Rees' Cyclopaedia," 1819, 

 we have all Muller's species ; while Leach, in his article " Crusta- 

 ceology," in the " Edinburgh Encylopsedia," 1820, only gives the D . 

 pulex. From the time when Muller's " Entomostraca" appeared, 

 up to this period, no additions to the species had been made — and, 

 with the exception of Ramdohr's memoir already mentioned, no ori- 

 ginal matter had been published concerning the genus — though, as I 

 have already observed in my former papers, this work of Ramdohr's 

 seems to have attracted no notice from any of the authors who suc- 

 ceeded him. In 1820, Jurine's splendid work on the " Monocles qui 

 se trouvent aux environs de Geneve," made its appearance after the 

 death of the talented and lamented author, in which we have a va- 

 riety of extremely interesting information, not only with regard to 

 their anatomy, but to their habits and manners. About the same 

 period, an elaborate and most excellent paper on the genus was read 

 before the Academy in Paris, by M. Straus, and published in the 

 " Memoires du Museum d'Hist. Nat." 1821. To these two authors 

 we owe the greater part of our knowledge with regard to these cu- 

 rious insects ; their labours and experiments having brought to light 

 much information with regard to their economy, which had escaped 



* Vol. u p. 15. 



