IN THE ANTENNAE AND PALPI OF DIPTERA. 



51 



Text -fig. 20, from a transverse section through the antenna of 

 Rhingia cmnpestris Meig., near the articulation, shows two sense- 

 pits, one on each side of the antenna ; they are widely open and are 

 guarded by stiff hairs, the sensory processes are small and regular. 

 The bases of the pits approximate very closely to each other and 

 are separated by a large branch of the antennary nerve which 

 closely embraces each pit. In Voliocella homhylans (text-fig. 21) 

 only one kind of sense-pit is found ; this has a somewhat narrow 



Text-figure 22. 



Transverse section through antenna of Volucella inanis. X 600. 



opening and is deeply sunk, the channel is guarded by a few 

 stiff hairs and the sensory processes are small and regular. Text- 

 fig. 22 shows a drawing of a ti^ansverse section of the antenna 

 of Volucella inanis. The section does not pass through the 

 opening of the pit. The processes here are of a different type, 

 they are rather short and sharply pointed, broadening towards 

 the base, and each process is separated from its fellow by a large 

 knob or block of chitin : cf. Rohler on Volucella (8). 



