396 1NSECTA. 



nerally small, unequal, and unidentated inferiorly. The scutellum 

 is tolerably large. These species compose the genus 



Hydrophilus, Geoff. Fab. Leach. Dytiscus, Lin. 



Here the sternal spine is strongly prolonged behind. The last 

 joint of the two anterior tarsi of the males is dilated in the form of 

 a triangular palette. The scutellum is large. They form the Hy- 

 drous of M. Leach(l). 



The larvae resemble a sort of soft, conical, and elongated worms, 

 furnished with six feet, and a large squamous head, more convex 

 underneath than above, armed with strong and hooked mandibles. 

 They respire by the posterior extremity of the body, are very vora- 

 cious, and do great injury to fish ponds by devouring the spawn. 



H. piceus, Fab.; Oliv., Col. 111,39, 1, 2. An inch and a half 

 long; oval; of a blackish-brown, polished, or as if covered with 

 a varnish; antennal club partly reddish; some slightly marked 

 striae on the elytra, the posterior extremity of which is rounded 

 laterally, and prolonged into a small tooth at the internal angle. 

 It swims and flies well, but walks badly. When held loosely 

 in the hand, its sternal spine sometimes inflicts a wound. 



The anus of the female is provided with two fusi, by means 

 of which she constructs an ovoid cocoon, surmounted with a 

 point, resembling an arcuated brown horn. Its external tissue 

 is a gummy paste, which, though fluid at first, subsequently 

 hardens, and becomes impervious to water. The ova it contains 

 are arranged symmetrically, and kept in situ by a sort of white 

 down. These cocoons float on the water. 



The larva is depressed, blackish and rugose, and has the 

 faculty of throwing back its brown, smooth, round head. This 

 enables it to capture the little Mollusca which navigate the 

 surface of the water, its back serving as a point d'appui or 

 anvil on which it mashes the shell in order to devour the ani- 

 mal it contains. The body of these larvae becomes flabby as soon 

 as they are caught. They swim with great facility, and are pro- 

 vided with two fleshy appendages beneath the anus which serve 

 to maintain them on the surface of the water, head downwards, 

 when they come there to respire. According to M. Miger, to 

 whom we are indebted for these observations Ann. du Mus. 

 d'Hist. Nat. XIV, 441 the larvse of other Hydrophilii are de- 

 prived of these appendages, and neither swim nor suspend 



(1) Zool. Miscel., Ill, p. 94. 



