401 



— Wings with distinct surface hairs; third vein ending appreciably 



farther in fi'ont of apex of wing than fourth ends behind it 



Tanytarsus (p. 484) . 



7. Wings with distinct surface hairs Metriocnemus* (p. 497). 



— Wings l)are 8 



8. Thorax with a distinct longitudinal furrow ; antennae in both sexes 



short-haired and with 7 joints (2-1-5) . .Clutsnuttonotuf; (p. 499). 



— Thorax without median furrow; antenna? of male with more than 7 



joints 9 



9. Apical portion of lateral arm of hypopygium not recurved, un- 



armed at apex on inner side (PI. XXXVII, Fig. 16) 



PscudocliironojHus^ (p. 500). 



— Ai)ical portion of lateral arm of hypopygium recurved, generally 



armed on inner side at apex with one or more thornlikc proc- 

 esses 10 



10. Legs conspicuously bicolored, black and white; eyes hairy 



Cricofopus (p. 501). 



— Legs not conspicuously bicolored, either black or brown, or if paler 



without sharply contrasted colors 11 



11. Posterior branch of cubitus conspicuously bisinuate (PI. XXXV, 



Fig. 9) Camptoclndius (p. 507) . 



— Posterior branch of cubitus either straight or slightly sinuous 



Ortliocladius, sens. lat. (p. 512) . 



N. B. The genera Tersesthes Townsend and Eutany-pus Coquillett are unknown 

 to me. 



Key to Larv.^I 



1. Eleventh segment wuth latero-ventral blood-gills, which arc usually 



very long and situated low 2 



— Eleventh segment without blood gills 7 



2. Only one pair of blood gills on eleventh segment, situated high on 



side at posterior margin, and occasionally very short or even 



*Eurjicnemu.'i, whic-h has been recorded from New Jersey, differs from Metrioc- 

 nemus in having the mesonotum conically produced in front, and the hind tiliia* dilated 

 and hairy. I have not s-een Illinois specimens of this genus. A genus, Brillia, has 

 } een erected by Kieffer for the reception of those species of Metriocnemiis that have 

 the hypopygium with apical portion of lateral arm bitid. At least one . American 

 species belongs to Brillia. 



tThis genus is intermediate between Chironomus and Orlhocladiitu, resembling 

 the former in the structure of the hypopygium and the latter in venation and in having 

 the basal joint of the fore tarsi conspicuously shorter than the fore tibia\ The species 

 described under the name Chironomris pseudoviridis, n. sp., in this paper shows a much 

 closer approach to the typical Chironomus, and I therefore leave it in that genus 

 though the length of the basal joint of the fore tarsi is not equal to that of the fore 

 tibia", and the hind tibiae have an apical spur instead of a comb of reguJar, closely 

 placed spinules. 



+ Species without page number are not treated in text. 



