IN THE ANTENNA AND PALPI OF DIPTERA. 



41 



MYCETOPPIILIDiE (Text-figs. 5, 6), 



Turning to tlie palps we find an entirely new modification of 

 the sensilli ; instead of occurring singly each one sunk in its 

 own pit (Tipulidfe), or arising singly from the surface (Chiro- 

 nomid«), they are grouped together and sunk in a large pit some 

 distance below the chitin in the tissue of the palp. This is a 

 " sense-pit," comparable to those of the later families. The j)it 

 lies in the second joint and thei'e is one in each palp. The sen- 

 sory processes are long and thin and spatulate. Text-fig. 6 is a 

 drawing of a transverse section showing the pit and its ojiening ; 

 text-fig. 5 is from a longitudinal section, showing the pit but 

 not its orifice. 



BiBioNiD^ (Text-figs. 7, 8). 



In some species of this family the multiple groups of sensilli, 

 or sense-pits, occur in both antennae and palps. 



Text-figure 7. 



Longitudinal section through the antenna of Bibio marci. X 600. 



