74 THE HYDRADEPHAGA. 



amongst the leaves of the water Crowfoot, or emitting 

 their peculiar sucking noise as they lazily sink out of 

 sight, the Fishes are sure to have an excellent repre- 

 sentative in the nest-building Stickleback, the delight 

 of very juvenile anglers ; and the amphibious Frogs 

 and Newts ably assist in maintaining the interest of 

 the Vertebrata. Truly our pond may afford material 

 enough for philosophic contemplation. 



I have said nothing as yet about Insects, but ento- 

 mologically considered, the dirtiest pond is of more 

 importance than even the ocean itself. A great 

 number of insects, belonging to four of the principal 

 orders of these creatures, are inhabitants of the fresh 

 waters, some during the whole course of their lives, 

 others only during their preparatory states ; and the 

 larvae of many of them are even provided with bran- 

 chial organs, to adapt them for respiration through 

 the medium of the water. 



Numerically the Beetles occupy a very respectable 

 position amongst aquatic insects, and the greater pro- 

 portion of them form a natural group, which, both in 

 structure and mode of life, is evidently closely allied 

 to the preceding tribe. In these insects, which con- 

 stitute the tribe of the HYDRADEPHAGA*, Aquatic 

 Predaceous Beetles or, shortly, Water Beetles, we 

 find the outer lobe of the maxillae again converted 

 into a palpiform organ, so that, like the Geodephaga, 

 they appear to possess six palpi. The maxillae them- 

 selves also terminate in a sharp hooked point, but the 

 mandibles, although still powerful organs, do not 

 cross in the manner of those of the Ground Beetles, 

 and the hind legs are elongated and flattened, so as 

 to render them efficient organs for swimming, whilst 

 * Gr. liudor, water, adephagos, ravenous. 



