20 



LABORATORY DIRECTIONS 



i 27. (26) Usually with four pairs of legs; in some cases with 

 two or three pairs but in these head, thorax, and abdomen are all 

 fused together. Respiration never by means of gills 



CLASS ARACHNIDA 



2 & (33) Abdomen bearing prolegs on at least some 

 somites 29 



29. (30) Abdomen with five pairs of prolegs and with no 

 spiracles at apex of abdomen ORDER LEPIDOPTERA (larvae) 



30. (29) Prolegs on last abdominal somite only 31 



31. (32) Abdominal segments each with a pair of long lateral 

 filaments or provided with conspicuous tufts 



, ORDER NEUROPTERA (larvae) 



-gills 



ng. 11 rig. 12 



Stonefly nymph Damsel fly nymph 



Hg. 13 

 Dragonfly nymph 



Fig. 14 

 Mayfly nynph 



32. (31) Abdominal segments without long lateral filaments 

 or conspicuous tufts ; often with minute gill filaments. Cylindri- 

 cal larvae, generally living in portable cases 



ORDER TRICHOPTERA ( larvae ) 



33. (28) No prolegs on abdomen 34 



34. (35) Labium, when extended, much longer than head; 

 at rest folded upon itself like a hinge and extending backward 

 between the bases of the forelegs ORDER ODONATA (nymphs) 



35- (34) Labium not capable of extension beyond head 36 



36. (43) Biting mouth-parts 37 



