Animals of the Mississippi Bottoms near Quincy. 157 



except in one of the more stagnant bodies of water, but were 

 probably present in all. These insects pass the winter in the 

 winged state, hid away in crannies. The larva; swim head 

 downward, and are the "wigglers" of neglected cisterns and rain 

 barrels. The food during aquatic life is probably decaying 

 organic matter. 



Corethra sp. 



The larvffi of this genus are small, worm-like creatures, 

 those from Quincy about .32 inch long and .028 inch in diame- 

 ter. The body is cylindrical, tapering towards the posterior 

 extremity. The head is provided with a perplexing variety of 

 structures for the perception and management of food, includ- 

 ing eyes, antennas, biting jaws, and a number of other tactile 

 and prehensile appendages. In front of the eyes the head re- 

 sembles a truncated cone, and at the blunt front extremity is 

 attached a pair of antennae consisting each of a long basal seg- 

 ment, from the free extremity of which arise from three to five 

 long, curved, and tapering rods. Near the posterior end of the 

 body IS a series of long, plumose filaments. The body is beau- 

 tifully transparent in life, and within it may be seen, near each 

 extremity, a pair of pigmented, kidney-shaped respiratory sacs. 



The pupffi may be distinguished from those of the next 

 genus by the presence on each side of the thorax of an odd, 

 bladder-like respiratory structure, the two resembling a pair of 

 ears. At the posterior end of the body is a pair of large fan- 

 shaped fins, by means of which the pupae swim freely in the 

 water. The adults are small, weak, obscurely-colored gnats, 

 which are not often observed. Two species of Corethra are 

 recorded from this country. 



Our larvae resemble those of the European Corethra pi iimi- 

 cornis, but differ apparently in some details of form, — as in the 

 shape of the eyes, and of certain leaf-like tactile appendages in 

 front of the mouth. 



The eggs are laid enclosed in a gelatinous material, 

 arranged spirally in a single series in disk-shaped masses, and 

 float at the surface of the water till the young larvae emerge. 

 This occurs about a week after the eggs are laid, but probably 

 the time varies greatly with the temperature. 



