WATEE-BUGS, WATEE-SCOEPIONS, ETC. 239 



with the exception of the lower parts of the posterior pair, 

 which are about the same colour as the iasect's back. 

 C. Geoffroyi, like Notonecta glauca, has a fringe of hair 

 round the extremity of its body. 



C. Sahlbergi is more abundant than the preceding species, 

 which it resembles in appearance, but it is about haK the 

 length, and less than half the width, of its great relative. 

 This insect will live for a long time in an aquarium, where 

 it wiU give very little trouble. 



Besides the above, G. striata, C. moosta, and C. fossarvmi, 

 axe the commonest members of this genus, the different species 

 of which are very di£B.cult to distinguish. 



Besides the Notonectce and the Corixce, there are other 

 members of this family, such as Plea minutissima, closely 

 related to the former, and the CytnaticB and Sigarce, allied 

 to the latter, which may be kept in the aquarium, but which, 

 I think, give more trouble to feed and to keep than most 

 aquarium-owners would care to bestow upon them. 



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