198 NEW YORK STATE MUSEUM 



qq Male claspers stout ; abdomen gray, 

 segments with pale margins 



62a. t e n t a n s 



pp Male fore tarsi with long hairs; fore 



metatarsus about one fourth longer 



than its tibia ; abdomen with a tinge 



of green. (= intermedin s) 



63. prasinus 



Auxiliary key to species of Chironomus (sens, lat.) 



This key contains those species of the gi'oup Chironomus, the 

 descriptions of which are too brief or imperfect to permit of a place in the 

 foregoing or in the keys which are to follow. With but three exceptions 

 the species contained in it were described by Francis Walker : 



a Abdomen dark. Species with brown, gray or black thorax, usually not 

 striped 

 h Hairy black species, 7.5 mm. long ; wings white with fuscous costa ; 



halteres a dirty ochre ; Arctic species 64. polaris Kirby 



bft Not as above 



c With dark halteres 



d Species 5 mm. or more in length ; legs dull yellow ; hairy ; fore 



feet very long 65. attenuatus 



dd Less than 2 mm. in length 



c Length 2 mm. ; chest thick ; wings white; bare; male 



66. crassicollis 



cc Length 1 mm. ; wings hyaline ; hairy? 67. fimbriatus 



CG With pale halteres 



d Tibiae and tarsi with black articulations ; black species ; 4.5 mm. 

 long ; abdomen yellow at base ; wing with cross band ; bare 



68. nigritibia 

 dd Not as above 



e Gray species; abdomen black with white rings; length 6mm.; 



Arctic species 69. b o r e a 1 i s Curt. 



cc Brown species 



f Species 6 mm. long. Thorax reddish striped, pleura whitish ; 

 abdomen dark brown, incisures paler; wings whitish, bare; 



male 70. a 1 b i s t r i a 



ff Species less than 4 mm. in length 



g Length 3.5 mm. Thorax brown, gray-striped ; halteres yel- 

 low ; wings hairy? male 71. b r u n n e u s 



gg Length 1 mm. Thorax brown; halteres pale brown; wings 



hairy? 67. fimbriatus 



aa Abdomen usually pale; species with green, pale red or yellow thorax; 



striped, excepting in a few of the palest 



b Abdomen dark brown, or if not, then with black markings or margins 



on the anterior segments 



c Posterior margin of segments black: thorax with broad black 



stripes ; scutollum black : length 5 nnii. ; male. . . .50. j u c u n d u s 



