NO. 2 



DRAGONFLY LARVA — SNODGRASS 



13 



Fig. 5.—Amx Junius (Drury), larva, structure and mechanism of the labium. 



A, the labial musculature, except muscles of the elbow (G). B, base of post- 

 mentum, and articular rod, left side. C, head with labium projected. D, diagram 

 of retracted position of postmentum and labial muscles from head. E, same parts 

 in protracted position of postmentum. F, elbow region of labmm showmg attach- 

 ment of head muscles on prementum. G, same, showmg elbow muscles. H, base 

 of prementum, anterior. , , . 



ar articular rod of labium ; Cd, cardo ; d, lobe of lever arm of prementum ; 

 e fold of articular membrane; /, median tongue of e; g, fibrous ligament; h, 

 hinge of labium on articular rod ; liAp, hypopharyngeal apodeme ; Hphy, hypo- 

 pharynx ; k, accessory flexor muscle of prementum ; /, tensor muscle ; Ivr, lever 

 arm of prementum; Pip, palpus; Pmt, postmentum; Prmt, prementum; Int, 



16 tentorial muscle of hypopharyngeal apodeme; 20, apodemal (flexor) muscle 

 of prementum; 44, tentorial (extensor) muscle of prementum; 46, abductor 

 muscle of labial palpus ; 47, adductor muscle of same. 



