98 ON THE ANATOMY OF THE FLY. 



The nerve of the halter, on entering the base, divides into 

 several branches, the greater part of which end in nerve cells 

 immediately below the corpuscles above described ; but a 

 large branch traverses the pedicle and ends in loops and nerve 

 cells in the globe. 



Before entering into any speculation as to the function of 

 the halteres, I shall describe some closely allied structures, 

 which I have named the wing organs. These are corpuscles 

 exactly like those in the halter, arranged in rows and groups 

 on the sub-costal nervure of the wing (Plate VIII., fig. 7). 

 These corpuscles usually have a smoky tint, but I have no 

 doubt as to their identity with the structures I have described 

 in the halteres. They disappear in the same manner when 

 the nervure is crushed. I have not, however, been fortunate 

 enough to see them in profile. According to Dr. Braxton 

 Hicks, they are very constant in insects in the same part, as 

 well as on the sub-costal nervure of the posterior wings. They 

 are supplied with nerve filaments, like the organs at the back 

 of the halter. 



These corpuscles, as well as those of the halteres, are opaque 

 when they first appear in the pupa, and I have frequently 

 observed those of the wing quite black and opaque in the 

 perfect fly, as if their development had been arrested. Each 

 of the wing organs seems to be situated under an oval convex 

 portion of the sub-costal nervure, corresponding to the ridges 

 of the halteres. Owing to their minute size, however, it is 

 almost impossible to be certain whether these are convexities 

 or depressions. There does not appear to be the slightest 

 thinning of the integument ai these points. 



Looking only to the structure of these organs, I am inclined 

 most strongly to regard them as auditory. The corpuscles 

 are, I believe, otoconia. It is true, they are not acted upon by 



