13RITISH HYDRACHNIDiE. 209 



not close together like the adult. The length of the larva is about 

 0*48 mm. The form of the nymph is very much that of the adult, 

 only smaller. 



The adults vary very much in size, but I have endeavoured to 

 give a mean measure. To arrive at this I have measured about 

 forty specimens. Neuman says the average size is 4 to 5 mm. I 

 have described their usual shape as egg-shaped or ovoid, but I 

 have taken two or three specimens which were quite unelliptical in 

 shape, like Koch's figure of Eylais confinis. It may have been 

 this shape which led Koch to think he had found another species. 

 Koch's other figures of Eylais appear to be the common shape. 

 So are the figures of Miiller, Duge, Neuman, and the little figure 

 in the Micro. Dictionary. 



In 1885, when Science Gossip published those beautifully 

 coloured plates, afterwards discontinued on account of the cost, 

 there appeared a plate by E. T. Draper in January over the name 

 of Eylais extendefis^ which, it will perhaps be as well to point out, 

 is not an Eylais, but one of the Limncsia. Dr. George, of Kirton- 

 in-Lindsey, pointed this out at the time to the Quekett Club, but 

 I do not think the error was ever corrected in Science Gossip. It 

 is a swift and powerful swimmer and easily kept in confinement. 

 I have kept a great number alive in tubes for weeks at the time. 



The majority of the references given are merely records of this 

 particular Hydrachnid, having been found at such a place and at 

 such and such a time ; but others are particularly interesting, and 

 should be seen and read by the student in this particular branch 

 of pond life. 



Genus XL — Limnocharis (Latreille). 1796. 



(Latreille, Precis des Caractlres des hisectes, p. 181.) 



All legs without swimming-hairs ; eyes approximated to median 



line of body. Body soft and varied in shape. 



Limnocharis holosericea (Latreille). 



Bibliography : — 



1755. — Roesel., Insektenbelustigunge?i, III., p. 25. 



1758. — Acariis aqiiaticus. Linne, Fauna Suecica, ed. 2, sp. 1978. 



1778. — De Geer, Metnoires poicr Vhistoire des Insectes, VII., p. 149 



—152, PI. IX., Figs. 15—18. 



