MAY FLIES AND MIDGES OP NEW YORK 89 



Imagines 



NOTE. In counting the antennal joints the large basal joint is included, 

 but not the hidden first joint. 



a Wings absent or rudimentary 



6 Wings reduced to mere vestiges, legs short and not slender, antenna 

 with seven joints, mouth parts rudimentary, pl.36, fig.13, female 



14. Clunio 

 66 Rudimentary wings reaching at least to the end of the first abdominal 



segment J 



c Halteres wanting, wings in the form of a flattened racket, tarsal 

 claws with a little subapical tooth. Palpi f our- join ted ; antenna 



five, ( ?) jointed 10. B e 1 g i c a 



cc Halteres distinct 



d Palpi four- jointed ; antenna of the female four-jointed, of the male 



six-jointed, pl.35, figs. 16, 21, 22 11. E r e t m o p t e r a 



dd Palpi two- jointed ; antenna of the female six-jointed 



e Second joint of antenna like those following, monilliform, pl.37, 



figs. 5, 6, 7 ~. 12. H a 1 i r y t u s 



ee Second joint longer than those following; male antenna also 

 with six joints, pl.35, figs. 4 to 9. ..13. Psamathiomyia 

 aa Wings present 



6 The M-Cu crossvein present (i. e., cell M closed by a vein), pl.37, fig.24 

 c Antenna with twelve or more joints 



d Antenna with fourteen joints usually plumose ; fourth tarsal joint 

 usually shorter than the fifth ; wing bare, pl.30, fig.13, male 



35. D i a m e s a 

 dd Not as above 



e Antennae with fifteen joints both in male and female; plumose 

 in the former ; the vein M simple, pl.27, figs. 1 to 15 



(Group T any pus) 

 f Wing bare 



g Fork of the cubitus petiolate 15. P r o c 1 a d i u s 



gg Fork of cubitus proximad of crossvein 



16. Anatopynia n. geu ; 

 ff Wing pubescent 



g Fork of cubitus proximad of crossvein 



h Antennae of male and female each with fifteen joints, R 2 



and R 3 distinct 17. A b 1 a b e s m y i a n. gen. 



hh Antennae of female with twelve joints, the male with fif- 

 teen joints, R 3 indistinct (Australian genus) 



18. Isoplastus 



gg Fork of cubitus petiolate 19. T a n y p u s 



ee Antennae with twelve or fourteen joints ; wings hairy ; cubitus 

 not forked ; anterior crossvein long and very oblique, pl.37, 



fig.16 20. Pentaneura 



cc Antennae with less than ten joints 



d Crossvein near basal third of wing, pl.37, fig.ll. Antennae about 

 eight-jointed (Chile) 21. Podonomus 



