2 DESCRIPTION OF INSECTS 



fallen trees, under bark or on flowers, ^'c. They generally 

 run briskly when disturbed, and many species diffuse a foetid 

 odor, or discharge a peculiar, pungent, acetous gas. 



The Dytiscii are much less numerous than the preceding, 

 but are equally nourished by animal food. They inhabit the 

 waters, occasionally visiting the surface for the purpose of 

 respiration ; they move with rapidity and ease through the 

 water aiid the air, but on land their gait is embarrassed by 

 the natatory form of the posterior feet. 



The Gyrinii, which are now included in the same family 

 with the Dytiscii, are comparatively few in number of 

 species, and those few are so intimately united in nature by 

 a similarity of character and habit, that no division has yet 

 been found necessary in the genus, which still remains un- 

 changed as it was first established in the artificial system. 

 These insects, like those of the preceding Linntean genus, 

 are insectivorous and aquatic ; they do not, however, like 

 them, remain at the bottom to seek their prey, but chiefly 

 confine themselves to the surface. They describe graceful 

 curvatures or gyrations on the surface of the water, with a 

 pleasing facility of movement, without exhibiting to the eye 

 the oar-like feet by which that celerity is effected. When 

 alarmed, they dive to the bottom with swiftness, carrying 

 with them a globule of air, that their respiration may 

 not be suspended. When irritated, they eject a lactescent 

 fluid, which, in many instances, diffuses an agreeable odor, 

 somewhat similar to that of the Calycanthus floridus of bo- 

 tanists. They fly with much ease and chiefly at night, but 

 their movements on land are uncouth and embarrassed. 



After thus briefly noticing the most prominent features 

 exhibited by these insects, it may be proper to observe, that 

 the descriptions are drawn out from such specimens only as 

 have fallen under my own observation, and which I had an 

 opportunity of examining and comparing together, in order 

 tlie more effectually to indicate their differential characters. 

 The individuals are chiefly preserved in my cabinet ; and for 

 such as I do not possess, I have carefully referred to those 

 collections from which I have described them. I have scru- 



