60 



MR. K. M. 8M1TH ON CHRTAiN SENSE-ORGANS 



Fannia. Tliis shows one large pit and one small one ; the sensory- 

 processes vary in shape, those in the large pit are pointed while 

 those in the smaller are like a curved finger : this is unusual in 

 the same insect ; there are also large thin-walled processes {Sp.) 

 arising directly from the general surface. Text-fig. 36 is from a 



Text-figure 37. 



Transverse section of the antenna of an undetermined Antliomyid. X 600. 



longitudinal section through the antenna of an undetermined 

 species (either Mydcea or Fhaonia). It illustrates a sense-pit and 

 long, rather sickle-shaped processes, very profusely scattered on 

 the general surface. Text-fig. 37 is a transverse section of the 

 antenna of a large Antliomyid, showing a pit and its contained 

 processes. 



MusciDJ-: (Text-figs. 38 & 39 and Pis. II., III., IV. figs. 4-10). 



The antennae in this family possess by far the largest number of 

 pits found in any of the Diptera examined ; they do not approach 

 those of the Syrphids in beauty and complication but are rather 

 small and regular. As far as can be ascertained thei-e are no 

 solitaiy sensory processes on the surface of the chitin, bvit the 

 sense- pits vary greatly in size, some being very small, with only 

 two or three processes. Text-fig. 38 shows part of a transverse 

 section through the antenna of Musca domestica. It illustrates a 

 very beautiful pit, with complex chitinous "basket-work" in the 

 long channel leading inwards from the orifice. The sensory pro- 

 cesses are finger-shaped and regular ; the whole organ with its 

 large radiating cells gives somewhat the appearance of a fan. A 



