THE LARVAL AND PUPAL STAGES OF THE BIBIONIDAE. 



225 



The spiracles of the first segment are situated laterally near the posterior boundary 

 of the segment. Dorsally the segment bears two rows of processes, each row 

 containing eight processes, the lateral processes of the second row being slightly 



Fig. 7. Right mandible of larva of 

 Bibio marci, ventral view, x 100. 



Fig. 8. Right maxilla of 



larva of Bibio marci, 



ventral view, x 100. 



displaced forwards by the spiracle. Ventrally the segment bears three incomplete 

 rows. The first row consists of two processes ; the second of four, one pair near 

 the median line and the other pair lateral ; in the third row there are four processes. 



The second segment, which has no spiracles, bears a row of eight processes dorsally 

 and another row of eight processes ventrally ; the median pair in the latter row 

 is situated nearer to the anterior margin of the segment than the remainder. 



Fig. 9. Labium of larva 



of Bibio marci, ventral 



view, X 100. 



The third segment bears a pair of spiracles laterally towards its anterior margin ; 

 dorsally it bears a row of eight processes, and ventrally a similar number, of which 

 the middle pair is placed forwards as on the second segment. 



The fourth segment bears a pair of spiracles in a similar position to those on the 

 third segment. Dorsally this segment bears a row of eight processes, the lateral 



