9 ° 
Within each type great variation usually exists 
in the different species. The following are the most 
notable variations found :— 
1. The Frill .—-The width. The continuity of 
the frill around the whole of the margin of the upper 
surface or its replacement in the middle third by the 
floats. The extent of striation of the frill. The 
presence of a striated rim only. 
2. The Floats .—The position, placed forwards 
and encroaching on the upper surface, or laterally 
situated. The shape, oval, globular, or scallop-shell. 
3. The Lower Surface .—Whether ornamented 
or not with silvery reticulated pattern. 
It is obvious that the characters of the ovum 
are of considerable importance in the classification 
of Anophelines , and every care should be taken to 
describe these in as great detail as possible. 
Draw the ova of Anophelines with a camera lucida. 
To Mount Ova 
No thoroughly satisfactory method is known to 
us, but although imperfect, any of the following 
methods will give specimens in which some, at least, 
of the ova preserve most of their characteristics. 
1. Place the eggs on a slide which has been 
made slightly sticky with balsam, and then mount them 
in a drop of balsam and place a coverglass over them. 
2. Mount in ten per cent, formalin solution and 
ring the coverglass with glycerin jelly and then with 
cement. 
3. Mount in glycerine and ring the specimen, 
4. Mount in a drop of cedar-wood oil. 
