THE MYCETOPHILID.Tv OF NORTH AMERICA. 225 



as the diameter of the femur at the widest part; tarsal claws 

 toothed, empodium prominent. Wings (fig. 78) broad, longer 

 than the abdomen ; costa produced beyond the tip of K*-^-^, 

 almost reaching the tip of the wing; subcosta less than 1-3 

 the length of the wing, ending in the costa a little beyond the 

 point where the radial sector begins ; subcostal crossvein 

 present or absent; Ri ends about 2-3 the length of the wing, 

 R2+3 about as long as basal section of the radial sector and 

 ends a little beyond the tip of Ri, the R-M crossvein stout and 

 very short, the media arises near the base of the wing and is 

 represented by a delicate fold-like vein to the crossvein, beyond 

 which it is strong, and forks about half way from the cross- 

 vein to the base of R2-f-3; cubitus forks slightly proximad of 

 the M-Cu crossvein ; second anal vein may be produced to 

 margin or may be abbreviated. Contains recent as well as 

 fossil forms. 



Table of species. 

 a. ^^'ing immaculate ; subcostal crossvein absent, anal vein not 



reaching margin of the wing. i. aldrichii. 



aa. \\'ing with markings; subcostal crossvein present, anal 



vein reaches margin of wing. (fig. 78) 2. joJuisoni n. sp. 



I. Palccopla'yitra aldricJiii Johannsen. 

 1909. aldrichii ]oha.nn sen, Genera InsectorunijjMycetophilidje. 10. 

 Male. Length 4 mm. Head, face and antennos fuscous, 

 basal joint of the last and palpi yellow ; ocelli arranged in a 

 triangle. Thorax pale brownish, including pleura, sternum and 

 scutellum, the mesonotum with 3 confluent darker stripes, 

 metanotum dark brown, humeri and supra-pleural stripe yellow; 

 black setre arranged in 5 longitudinal lines, 3 on the mesonotum 

 and 2 on the lateral margin; scutellar setce fine and numerous, 

 but little longer than those on the humeri. Abdomen brown, 

 darker apically, with black setulre ; hypopygium as described 

 for the genus. Cox<x and legs pale yellow, tarsi infuscated, 

 fore metatarsus about .7 as long as its tibia ; spurs yellow. 

 Wings hyaline, with a very faint smoky tinge, heavier veins 

 brown, slender veins more yellowish; subcostal crossvein want- 

 ing, anal vein stout but not reaching margin of the wing. Hal- 

 ter es yellow. 



