Systematic Position and Structure 1 1 



are difficult to describe, yet most of the eggs are 

 easily distinguishable when you have the right light 

 on them. (For illustrations see Plates V. to VIII.) I 

 know of nothing harder to observe properly under 

 the microscope. The egg must not be too wet or 

 the sculpture is invisible, nor too dry or, in many 

 cases, the shell will shrivel ; if the light is not exactly 

 right, you see nothing but a black speck ; if it is 

 good, only a little patch of the pattern is visible at a 

 time. Alcoholic specimens are absolutely useless, 

 the membrane sticking so close to the egg as to 

 obscure all markings. Formalin specimens are not 

 very bad. 



The eggs are of a more or less oval shape, with a 

 hard, almost black, chitinous shell. Over this lies 

 a delicate, — filmily delicate, — white, transparent 

 membrane, which, in the eggs laid singly, is sculp- 

 tured in more or less hexagonal figures. Most of 

 the mosquitoes, contrary to the popular impression, 

 lay their eggs singly, instead of in a raft which 

 floats upon the surface. The single eggs, except 

 those of Anopheles, which have the membrane puffed 

 out at the sides to form a float, sink and hatch at 

 the bottom. Often there are small puffs inside the 

 hexagons, or there are spine-like processes of the 

 membrane. The raft eggs have the membrane so 

 tightly spread over the surface of the chitin that it 

 is almost impossible to ascertain whether or not 

 there is a sculpture, but the writer has seen very 

 minute knobs and also hexagons on some. The 

 smaller ends of these eggs generally possess a button 

 of chitin, covered by a small puff of the membrane, 



