24~c Canadian Arctic Expedition, 1913-18 



EXPLANATION OF PLATE III. 



Hypopygium of Nephrotoma arcticola; ninth tergite, dorsal aspect. 



" N. arcticola; outer pleural appendage. 



" Tipula hewitti; the same. 



" T. besselsoides; the same. 



" T. johanseni; ninth tergite, dorsal aspect. 



" T. diflava; the same. 



" T. diflava; lateral aspect; 9t. ninth tergite; 9 pi. ninth pleurite; 



9 s. ninth sternite. 



" Tipula arctica; ninth tergite, dorsal aspect. 



" T. hewitti; the same. 



Hypopygium of T. arctica; inner pleural appendage. 



" T. subpolaris; ninth tergite, dorsal aspect. 



" T. besselsoides; the same. 



Ovipositor of T. arctica; female sternal valves. 

 Hypopygium of T. subarctica; ninth tergite, dorsal apsect. 



" T. besselsoides; inner pleural appendage. 



Ovipositor of T. arctica; dorsal aspect. 



EXPLANATION OF PLATE IV. 



Fig. 44. Larva of Poecilostola, supposition; spiracular disk. 



" 45. " Tipula arctica; the same. 



" 46. " Stygerojris, supposition; the same. 



" 47. " Tipuline No. 2; dorsal aspect of entire larva. 



" 48. " Tipuline No. 2; spiracular disk. 



" 49. " Tipuline No. 3; the same. 



EXPLANATION OF PLATE V. 



Pupa of Tipula arctica; male, lateral aspect. 



" T. arctica; female, dorsal aspect. 

 Larva of Tipula arctica; labrum, dorsal aspect. 



" T arctica; mentum, ventral aspect. 



" Poecilostola, supp.; outer lobe of maxilla. 



" Poecilostola, supp.; mandible. 



" Tipula arctica; chsetotaxy of third abdominal tergite; dorsal aspect. 



" T. arctica; the same, third abdominal sternite; ventral. 



" Stygeropis, supp.; the same, third abdominal tergite; dorsal. 



" Stygeropis, supp.; the same, third abdominal sternite; ventral. 



" Tipuline No. 1; the same, third tergite; dorsal. 



" Tipuline No. 1; the same, third sternite; ventral. 



" Tipuline No. 2; the same, third tergite; dorsal. 



" Tipuline No. 2; the same, third sternite; ventral. 



" Tipuline No. 3; the same, third tergite; dorsal. 



" Tipuline No. 3; the same, third sternite; ventral. 



EXPLANATION OF PLATE VI. 

 Figs. 1, 2. Female of Tipula arctica Curtis (Photos, by Geo. H. VVilkins) 



