THE MALARIAL 3I0SQUIT0ES 99 



be covered with a reticulate hexagonal sculpturing-. At 

 the sides, in the middle, there appears a clasping mem- 

 brane with many strong transverse wrinkles. Seen from 

 above, the eg^ is black except for a clasping membrane 

 which nearly meets on the middle line in the middle 

 third of the body, but retires to the extreme sides for the 

 anterior and posterior thirds. At each end the color is 

 lighter, with a group of from 5 to 7 minute dark circular 

 spots. It is 0.57 mm. long. Eggs laid April 26th hatched 

 April 30th. Others laid May 13th and 14th hatched May 

 16th and 17th. 



The Larva. — The larva is quite as unlike that of Culex 

 pungens as is the egg. It differs in structure, in its food- 

 habits, and in its customary position, so markedly, that it 

 can at once be distinguished with the utmost ease. The 

 larva of Culex, it will be remembered, conies to the sur- 

 face of the water to breathe, thrusting its breathing tube 

 through the surface layer and holding its body at an an- 

 gle of about forty-five degrees with the surface of the 

 water. While in this position its mouth-parts are in mo- 

 tion and it is taking into its alimentary canal such minute 

 particles as may be in the water at that depth, but these 

 are naturally few in number and the larva descends at 

 frequent intervals toward the bottom to feed. The want 

 of oxygen, however, causes it to wriggle up again to the 

 surface at very frequent intervals. Its specific gravity 

 seems greater than that of water, so that it reaches the 

 surface only by an effort, and the writer has already 

 pointed out, in the case of Culex pungens, that when the 

 larva becomes enfeebled and is not strong enough to 



