198 NEW YORK STATK 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 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 

 ft Hairy black siiecies, 7.5 mm. long ; wings white with fuscous costa ; 



halteres a dirty ochre ; Arctic species 64. polaris Kirby 



&6 Not as above 



c With dark halteres 



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



feet very long 65. a 1 1 e n u a t u s 



eld Less than 2 mm. in length 



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



66. crassicollis 



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



CO 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; winj^s 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 



fffj Length ] 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 ; scutelUmi Mack : length ." iinii. : iiimIo. . . ..lO. j u c \i n d u s 



