SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I23 



Fig. 6. — Transformation of the labium. 



A, labium of a mature Anax larva containing the imaginal labium in early 

 stage of transformation. B, same at later stage, imaginal labium retracted into 

 larval postmentum. C, imaginal labium removed from B. D, same unrolled and 

 spread out. E, fully mature imaginal labium. F, imaginal labium of a libellulid. 

 G, section of adult libellulid head. H, head of same, lateral. 



Cb, cibarium ; dp, clypeus ; Cvx, neck ; dlcb, dilator muscle of cibarium ; eR, 

 epistomal ridge ; Fr, f rons ; iLb, imaginal labium ; IbPlp, labial palpus ; Lig, 

 ligula ; Lm, labrum ; Md, mandible ; Oe, oesophagus ; Phy, pharynx ; Pip, palpus ; 

 Plpg, palpiger ; Pint, postmentum ; Prnit, prementum ; slDct, salivary duct ; slO, 

 salivary orifice. 



