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only two, which arc the Gyrinidse and Dyticid*. 

 Mr. Kirby, also in the Fauna Boreali Americana, 

 adopts this twofold arrangement, and applies to 

 them the terms of Eunecha and Gyronecha. Dif- 

 fering from such high authorities, I am inclined to 

 consider the Gyrinidaj as a totally distinct group 

 which I name Gyrinoidea. It may be regarded 

 as an intermediate family, connecting as it does, 

 according to my views, the Dyticoidea and Hydro- 

 philoidea. The larva of true Gyrinus in appearance 

 resembles a Scolopendra. It is carnivorous, and is 

 therefore allied to Dyticus ; the connection with 

 the Hydrophilidae, however, is not so apparent. 

 I think it is not improbable that the larvae of 

 Dineutus MacLeay, will eventually be found to 

 approach in form the larvae of the spine-winged 

 species of Hydrous, In the metallic splendour 

 of some of the individuals of both genera, in the 

 armature of the wings, in the partially carnivorous 

 habits of Hydrous, and the silkiness of the coccoons, 

 the Gyrinidse. will be found evidently more allied to 

 the Hydrophilidae, than the Dyticidse. At present, I 

 believe, among the genera composing the latter 

 family, not a single species has yet been found 

 which has spined wings, should such occur, it 

 will most probably be the connecting link so much 



