Chitinoits Tunnels of Head 



89 



(clypeus), which is prominent in the larva, as in most 

 insects. The small part of the clypeus which remains is 

 seen as a narrow transverse plate, separated by a suture 

 from the epistome or anterior clypeus, which carries the 

 small triangular labrum (fig. 59). 



On each side of the suture between the clypeus and the Glutinous 



tmmels 



epistome is a rounded orifice, which leads into the interior of head. 



Fig. 59.— Head of male fl.v of C'hinmomus dorsaUs, front view. The 

 antennae are removed, with the exception of the large second joint (b) 

 which shows the place of attachment of the shaft, v.p, jsrocesses on the 

 vertex, s, transverse suture, o.r, orifice of chitinous cephalic cavity. 

 e, epistome. Ir, labnim. I, labella. mx.p, maxiUary pulp. 



of the head, dilating there into an irregular cavity, which 

 extends to the back of the head. The head is therefore 

 tunnelled through by a pair of cavities, whose walls are 

 stiffened by chitin, and are morphologically part of the 

 external surface (fig. 60). Muscles are seen in our sections, 

 which seem to pass from the tunnels to the bases of the 



