THE LARVAL AND PUPAL STAGES OE THE BIBIONIDAE. 



227 



The four Malpighian tubes join the ahmentary canal at the junction of the mesentcron 

 and hind gut, entering the canal by a short common duct on tlie dorsal side. There 

 no posterior caecum such as is found in connection with the alimentary canal 



of Bibio johannis. 



Fig. 11. Alimentary 

 canal of larva of Bibio 

 marci, lateral view, x 5; 

 c, caeca ; M, Mal- 

 pighian tubes ; oe, 

 oesophagus. 



Pupa. 



Elongate, cvhndrical, tapering gently to posterior end, abruptly at anterior 

 end Completely free from larval skin. Colour at first white, head and thorax ot 

 imago showing dark through cuticle later. Length from head to tip of abdomen, 

 (^ 12-5 mm • ? 15 mm. (fig. 12). Head with very slight, blunt, anterior, median 

 process ; a slight median dorsal ridge extending from the anterior median process 

 to posterior margin of thorax, dehiscence for emergence of imago occurring along this 

 ridge. Antennae extremely short, arising between bases of eyes, extending laterally 

 over eyes. In the males, eyes large and protruding ; in female, smaller and less 

 conspicuous. Labium elongate, semicircular ; labial palpi elongate, conica , extendmg 

 laterally. Dorsally, mo^t of head covered by prothorax, only eyes of male visible. 



