OSTEN SACKEN ON WESTERN DIPTERA. 295 



B. Abdomen black, with white spots or cross-bands on the hind 

 margins of the segments : 

 (b) Legs reddish : 



10. profusus n. sp. $ 9 . 

 (bb) Legs black : 



11. evidens n. sp. $ 9 ; 12. rejectus n. sp. 9 ; 13. nugator 

 n. sp. (<? ?) 9; 14. positivus n. sp. <? ; 15.5M<7ator n. sp.<? 9 , 



BB. Abdomen gray, with black spots : 



16. rattus n. sp. $ 9 . 



Aberrant species. 



17. cerussatus n. sp. £ 9 ; 18. nebulo n. sp. 9 . 

 Analytical table for determining the species. 



Antennal style fully aslongas the third antennal joint ; wings with 

 distinct brown clouds on the cross- veins aud on the bifurcation 

 (1) < of the third vein 18. nebulo n. sp., 9 . 



Antennal style much shorter than the third antennal joint ; wings 

 without distinct brown clouds, etc., (2): 



, 9 v i Third antennal joint red, (16): 

 ^' \ Antennae altogether black, (3) : 



/q x j Hind tibiae more or less red in the middle, (4) : 

 W \ Hind tibiae black, (9) : 



f Male : front tarsi with a conspicuous dense fringe of silvery pile ; 

 two last joints of middle tarsi with a disk of black bristles; 

 female : hind margins of abdominal segments white on the sides 

 only, sometimes very little, (7) : 

 Male : front and middle tarsi plain ; female : hind margins of 

 abdominal segments 2-5 altogether white, (5) : 



f Scutellum convex, black; the brownish pollen at the base, if any, is 

 hardly perceptible ; densely pilose with long, erect pile ; face in 

 r , J the middle with white pile, (6): 



' ^ | Scutellum flat, covered with dense gray pollen : longer hairs along 

 the edge only ; face altogether with black hairs, 

 (_ 10. profusus n. sp. 2 9 . 



( The fan-like row of hairs in front of the halteres is black, 

 (6) ) 4. montanus Lw., $ 9 . 

 ( The fan-like row of hairs, etc., is white 5. leucozonus, Lw., ? . 



,„. i Scutellum shining black, (8): 



( ' \ Scutellum with gray pollen 3. plausor n. sp., <? ? , 



c Abdomen with white pile on the sides . .1. callipedilus Lw., $ $ . 

 (8) ) Abdomen with black pile on the sides from the very base, 



I 2. cymbalista n. sp., $ 9 



-p. ( Abdomen gray, with black, shining spots.. 16. rattus n. sp., $ 9. 

 ' ' \ Abdomen black, with white cross-bands, (10) : 



i White cross-bands on the anterior margins of the segments, 

 (10) < 17. cerussatus n. sp., $ 9. 



( White cross-bands on the posterior margins of the segments, (11) : 



w 



