DISPOSAL OF EGGS 143 



deposited in the water and surrounded by a gelatinous substance. Busck found 

 about twenty-five of these eggs united in an ovate gelatinous mass, each egg 

 surrounded by its own spherical gelatinous envelope and supplied with an air- 

 bubble which helped to keep the mass afloat. Mr. Jennings has since repeated 

 this observation. The gelatinous matter furnished the first food to the newly 

 hatched larvae. 



So far Johlotia digiiaius stands unique, not only among the members of the 

 genus, but in the entire tribe of Sabethini, by depositing its eggs in a raft. Its 

 raft is a type entirely distinct from those previously described. It is flat and 

 circular in outline, instead of elongate and concave as in the egg-boats of Culex. 



Anopheles deposits its eggs separately in small numbers, upon the surface of 

 the water. The eggs lie upon their sides and are kept afloat by a peculiar struc- 

 ture, a partial envelope which is more or less expanded, particularly along the 

 median portion of the egg. This hydrostatic organ is variously shaped and de- 

 veloped in the different species of Anopheles. In one case. Anopheles turkhudi 

 of India, this apparatus is nearly obsolete and the only trace remaining is a 

 small rudiment concentrated near the larger end. In a remarkable Brazilian 

 anopheline, Chagasia fajardoi, the hydrostatic apparatus reaches a remarkable 

 development, completely surrounding the egg and forming a series of longi- 

 tudinal, remarkably constructed, air-chambers. 



So far as we are aware the eggs of all Anopheles are provided with the hydro- 

 static organ and are normally laid upon the water. The eggs of such a large 

 proportion of the species are now known that we can expect no exceptions. The 

 eggs of Anopheles turkhudi and Chagasia fajardoi, just described, probably rep- 

 resent the two extremes of modification of the hydrostatic organ. Recently H. I. 

 Cazeneuve claims to have found that in northern China Anopheles pass the 

 winter in the egg-state, the eggs being frozen into the mud and hatching when 

 thawed out. The observation evidently is based on an error in determination. 

 Cazeneuve has undoubtedly taken the males of certain species of Aedes (which 

 agree exactly in habits with his observations) for Anopheles on account of their 

 long palpi. This is the more excusable as several famous entomologists, in their 

 systematic work, have fallen into the same error and have described males of 

 culicines as Anopheles. 



The eggs of Bancroftia signifer are laid singly upon their sides, at the margin 

 of the water. These eggs are remarkable in that they are fastened down by a 

 gelatinous covering which extends all around them in the form of a broad, 

 curiously sculptured, rim. Megarhinus lays its eggs singly upon the water. 

 Goeldi found the egg-shells of Megarhinus hcemorrhoidalis floating separately 

 upon the water in little groups of from four to six and this has given rise to the 

 statement that the eggs are laid in chains. Green, in Ceylon, has obtained the 

 eggs of Megarhinus immisericors from a confined female and found that they 

 were scattered singly over the surface of the water. The eggs are regularly oval 

 and their surface is closely studded with spinose tubercles which hold the air 

 between them and keep the egg afloat. " The actual operation of egg-laying was 

 not seen, but the female was observed jerking itself up and down in the air just 

 above the water, and it seems probable that the eggs were shed at that time." 



