98 MODERN CLASSIFICATION OF INSECTS. 



of having eaten a large leach which disagreed with it, large portioniS 

 of it being discharged the following day, undigested, from the mouth. 

 According to Esper and Erichson they are, however, able to fast for 

 many weeks, and even months, but if they are kept out of the water 

 they die in a very few days. It is also requisite for them to ascend 

 repeatedly to the surface of the water for a supply of air for respiration, 

 where they may be observed in sunny weather, resting with the ex- 

 tremity of the body protruded above the surface, and their legs 

 extended at right angles. On approaching them, however, they im- 

 mediately dive to the bottom. Esper also ascertained that they are 

 very susceptible of atmospheric changes, indicated by their movements; 

 thus, when the air is agitated they remain at the bottom, but rising by 

 degrees and stationing themselves at different heights in the water, 

 according to the calmness of the weather. Hence, their internal or- 

 ganisation will not allow them (like the fishes) to remain without 

 access to the air; indeed, they may often be seen in a calm summer's 

 evening creeping up rushes to take flight, rising into the air almost 

 perpendicularly, until they are out of sight. Their descent is also 

 perpendicular, dropping with considerable force into the water. It 

 would also appear that it is by the reflection of the light upon the 

 surface of the water that they are informed of a proper place for their 

 descent, since I have several times observed specimens of various 

 Water-beetles falling with violence upon glazed garden frames, and 

 which they had evidently mistaken for water. The Rev. Mr. Bird 

 has occasionally caught aColymbetes, which has been attracted into a 

 room by a lighted lamp in the evening. (^Ent. Mag. No. 6.). On the 

 ground their motions are rapid, although their fore legs alone can 

 serve them as legs. Some, as the Laccophili, whose hind legs are 

 thick, spring to a considerable distance. When laid upon their backs 

 the quick muscular action of the hind legs gives them a whirling 

 motion. The small species may occasionally be observed resting upon 

 the flowers of aquatic plants, to which they have crept, either to 

 luxuriate in the sun, or to gain an elevation previous to taking flight. 

 They are to be found in all seasons of the 3'ear, but more frequently 

 towards autumn. During the winter, some remain in the water, or 

 bury themselves in the mud in a torpid state ; others retain their 

 agility, and may be seen coming to take the air in places where the ice 

 is broken. I have even seen them swimming about in the water be- 

 neath the ice whilst I have been skatinsr on the surface. Some also are 



