NO. 8 ANATOMICAL LIFE OF THE MOSQUITO — SNODGRASS 



13 



sclerites in the lower labral wall known as the tormae. In a tipulid 

 larva (fig. 4 A) the tormae (Tor) are simple sclerites, each giving 

 attachment to a long muscle (mcl) from the frons. There is, there- 

 fore, no apparent reason why the similarly musculated sclerites of 

 the mosquito larval labrum (C,D, Tor) should not be the tormae. 

 On the other hand, Cook (1944b) has contended that the sclerites are 



Md 



Mx Hstm 



E IF™ **^ G 



Fig. 4. — The larval labrum and tormae. 



A, Tipula sp., underside of larval labrum. B, Culex sp., labrum of young 

 larva, anterior. C, Anopheles quadrimaciilatus, left labral brush and torma, 

 undersurface. D, Aedes aegypti, same. E, Toxorhynchites ratilus, anterior 

 view of larval head. F, Same, labral brush with torma and muscles. G, 

 Chironomus plumosus, underside of larval labrum. 



Ap, tormal apodeme; B, labral brush; Hstm, hypostomium ; Lm, labrum; 

 mcl, mcls, tormal muscle or muscles ; Md, mandible ; Mes, messorial teeth of 

 torma; Mx, maxilla; Tor, torma. 



a, connective sclerite between torma and brush; b, c, detached sclerites of 

 cranial wall ; d, e, anterior and posterior articulations of torma ; /, epipharyngeal 

 bar. 



not the tormae because he finds in chironomid larvae another pair 

 of muscles attached more dorsally and laterally on the labrum, which 

 he insists are the true tormal muscles. These muscles, however, would 

 appear to be the usual dorsal muscles of the labrum, which may have a 

 lateral position. Furthermore, Cook adds that the ventral muscles are 

 not tormal muscles because they arise on the clypeus, but what he calls 



