IN THE AJQTENN^ AND PALPI OF DIPTERA. 45 



Text-fig. 11 shows a portion of the antenna of Microchrysa 

 polita L., showing the " hands " in position ; the thin chitin which 

 forms the base of the structui^e is represented by cross-hatching. 



Much the same state occurs in the palp. Text-fig. 12 shows 

 a longitudinal section through the top of the palp of Oxycera 

 pulchella Meig., with one '' hand " and one large single sensory 

 process. 



Wesche describes very similar sense-organs in the antennre of 

 Stratiomys chamceleon. 



Tabanid^e (Text-fig. 13). Species examined determined by 

 C. G. Lamb. 



In the antennpe of the members of this famil}' studied is found 

 a return to the less complicated form of sensory structure. 

 There are two kinds of processes, a large straiglit type sunk singly 

 in a small pit, but projecting far _be}'ond the level of the chitin 



Text-fieure 13. 



Part of a transverse section of the antenna of Tabanus hromius. X 980. 



(text-fig. 13) : this is the trichoid type of sinsory process. There 

 arc also small shouldered processes, sunk singly veiy deeply in the 

 tissue of the antenna. There is little or no difference between 

 the sensory processes of Tahamts broniits L. ( 5 ) and Hcemaiopota 

 pliovialis L. ( $ ). I have been unable to find any special sensory 

 structure in the palps of this famil3^ 



AsiLiiD^ (Text-figs. 14-16). Species examined determined by 

 C. G. Lamb. 



In this group we return once more to the actual sense-pit. 

 Text-fig. 14 shows a longitudinal section through the antenna 

 of Laphria marglnata ; the chitin is enormously thick and the 

 entrance to the sense- pit is guarded by thick knobs and pro- 

 jections of chitin and interspersed with small pits containing one 

 or more sensory processes of varying shapes. The processes in 



