I 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 Ano-phelines 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. 



