FORM, GROWTH, AND CHANGE 45 



larva is able, lurking at the bottom of its native pond or 

 stream, to seize as prey any smaller or weaker insect that 

 happens to pass within its reach ; and when the mask is again 

 drawn back, the prey is brought within reach of the mandibles 



FIG. 24. 



A D, Nymph of Dragon-fly (Aesckna). A, dorsal view; 

 B, ventral view ; C, lateral view of head and thorax with 

 mask retracted ; D, dorsal view of head with mask ex- 

 tended ; E, head and thorax of larva of Tramea, lateral 

 view ; F, head of same, front view ; mask retracted, x ij. 

 ant, feeler ; ep, crown of head ; fr, frons ; cl, face ; Ibr 

 labrum ; oc, occiput ; e, eye ; pol, postocular lobe ; sm, sub- 

 mentum ; m, mentum ; h, hinge of labial mask ; II, lateral 

 lobe (palp) ; a, d, its hooks : ml, median lobe (galeae and 

 laciniae) ; n, pronotum ; pl 2 , pl 3 , meso- and meta-thorax ; 

 ex, haunches ; tr, trochanter ; fe, thigh ; th, shin ; ts, foot ; 

 ni, forewing rudiments ; w t , hindwing rudiments ; sp, 

 spiracles ; i 10, abdominal segments ; c, cercus ; c lt upper 

 appendage ; ai, dorsal appendix of abdomen ; ovp, ovipositor. 

 From Tillyard, " Biology of Dragon-flies ". 



