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 Jcey 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 

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



halteres a dirty ochre ; Arctic species 64. polaris Kirby 



66 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 



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



66. crassicollis 



cc 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. nigri tibia 

 dd Not as above 



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



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

 low ; wings hairy? male 71. brunneus 



gg Length 1mm. 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 

 6 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. jucundus 



