PACKAKD] INSECTS OF THE POND AND STREAM. 157 



and are articulated by an exquisite mecliauism to tlie body. 

 They are edged on tlie inner side witli a dense, long fringe 

 of exceedingly fine, white hairs, forming, with the flattened 

 leg itself, the blade of the oar ; and thus by a series of 

 rapid strokes the body is propelled onwards. The fore legs 

 are short and thick, and in the males modified into a clasp- 

 ing organ, the three basal joints of the tarsus being broadly 

 dilated and consolidated into a large disk, covered with 

 " many minute funnel-shaped suckers, two or three of which 

 are much larger than the others." The G^^rinus is less a 



Fig. 125. 



Male and Female Dytiscu3. 



diver than a surface swimmer. It is a very sociable insect, 

 forming little swimming parties on the surface of the water. 

 In the course of its gyrations it manages to pick up a com- 

 fortable livelihood of small beetles and flies which fall into 

 the water. When disturbed it dives to the bottom. Unlike 

 the other water beetles it has very large fore legs and re- 

 markably short middle and hind legs, and Hies about in the 

 night, at daylight slipping quietly' into some pool. On 

 being handled it emits a disagreeable, whitish, milky fluid, 

 which is probably distasteful to its enemies. All the other 



2 'J 



