COLEOPTERA. 471 



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

 are arrang-ed symetrically, 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 devoiu- 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, 

 Avhcn 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 larvae of other Hydrophilii are de- 

 prived of these appendages, and neither swim nor surpend 

 tliemselves like those of which we have been speaking. The 

 females of these species swim withdifficidty, and cany their ova 

 under the abdomen enclosed in a silken web; but these species 

 belong to the last subgenera of this tribe. 



The Hi/drcphilus proper of Leach consists of species in which 

 the tarsi are identical in both sexes, and not dilated, the pectoral 

 spine terminates Avith the post-sternum, and in which the scutel is 

 proportionally smaller*. 



In all the following Hydrophilii, the two intermediate joints of 

 the antennal club are exactly transversal, of a regular form, not pro- 

 longed into a tooth at either extremity, and without any space be- 

 tween them; the last is obtuse or rounded at the end. The pectus 

 exhibits neither carina nor spine. The tarsi are less, or not at all 

 fitted for natation, but slightly or not ciliated, and terminated by 

 large, equal, and simple hooks. 



Those in Avhich the maxillary palpi are hardly longer than the 

 antennae, Avith the last joint shorter than the preceding one, and 

 cylindrical, in which the body is low, and the elytra are truncated 

 at the extremity, or very obtuse, form the genus 



LniKEBius, Leach-\. 



Those, in which the maxillary palpi are hardly longer than the 

 antennae, with the last joint as long as the preceding one or longer, 

 and almost oval, and in which the body is convex, are comprised by 

 the same English savant in two genera. In one of them, the 



Hydrobius, Leach, 



The eyes are depressed or but slightly convex ; the anterior extre- 



* To the Hydrous, Leach, besides the jnceus,, refer the following species of 

 Fabricius : the ater, oUvaceus, i-ufipes, &c. Those, which the latter calls caraboides, 

 (Uipticus, &c., are Hydrophili properly so called of Leach. 



f H, griseus, iruncatellus, Fab, 



