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. (= intermedins) 



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 

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



halteres a dirty ochre ; Arctic species 64. polaris Kirby 



1)1) 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 



QQ. crassicollis 



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



cc 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 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 a 



ff Species less than 4 mm. in length 



g Length 3.5mm. 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 



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



striped, excepting in a few of the palest 



h 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 



