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. (=intermedius) 



63. prasinus 



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



This key contains those species of the group 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 

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



halteres a dirty ochre ; Arctic species 64. polaris Kirby 



6B Not as above 



c With dark halteres 



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



feet very long 65. attenuatus 



dd Less than 2 mm. in length 



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



66. crassicollis 



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



cc With pale nalteres 



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

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



68. n i g r i t i b i a 

 dd Not as above 



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



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



ee 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 n 



ff Species less than 4 mm. in length 



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



low; wings hairy? male 71. brunneus 



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



hairy? 67. fimbriatus 



na 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 ; scutellum black : length 5 mm. ; male. . . .50. j u c u n d u s 



