148 THE ANIMAL KINGDOM. 



HALTERES OF BLOW-FLY. 



These, if mounted carefully in balsam, have become 

 transparent; we see that they consist of three parts, the 

 base, shaft, and head. The organs in question are at the 

 base, two distinct groups of vesicles, which look like dots 

 arranged in rows. The upper group is in spiral lines, the 

 lower is on a broad flat surface, and only on one side. Each 

 vesicle is a small sac, filled with fluid, and over-arched by 

 a protecting hair, and when a good side view is obtained 

 they are seen to be quite spherical. 



The two naturalists, Dr. Hicks and Mr. Purkiss, who 

 have noticed these organs, suppose them to be olfactory 

 vesicles. There is a very large nerve given off from the 

 great thoracic ganglion into the halteres, larger even than 

 those branches which pass into the wings and legs of flies, 

 which makes it very likely that in these very small appen- 

 dages lie a great sensitiveness of some kind. No less than 

 360 of these vesicles are found in the halteres of Bhingia; 

 and for what purpose ? 



Dr. Hicks justly remarks, that it is scarcely for hearing, 

 as they are so near the buzz of the wings, and themselves 

 in constant motion, so that other sounds would be drowned ; 

 but that the current of air produced by this very fluttering, 

 and also the position of the halteres near the largest thoracic 

 spiracle, make it extremely probable that they receive the 

 floating odours in the air, and communicate them to the 

 brain, or cephalic ganglion, directing thus the Blow-fly to 

 the carrion, the Bhingia to the flowers. 



HALTERES OF TABANTJ8. 



" These are very similar to those of the Bhingia, with 

 the addition of seven vesicles on the shaft of the halteres 

 to the upper part of the facet of the ridge, and another 



>up of eight or nine beneath the ridge opposite the 

 er facet."* 



* See ' Journal of the Proceedings of the Linnean Society of London,' 

 November, 1856. 



