502 



legs of a species are so colored that one has some hesitation in assign- 

 ing it definitely to either genus. OrtJwcladius politits is a case in 

 point. The legs in politiis are bicolored, but the colors are not 

 sharply contrasted. The eyes possess distinct surface hairs, however, 

 which seems to indicate a closer affinity with Cricotopus than with 

 Orthodadius. A subgenus of Orthocladiits, Trichocladius, has been 

 erected by Kieffer for the reception of those species of Orthodadius 

 which have hairy eyes. This subgenus is said to be distinguished 

 from Cricotopus by the absence of pulvilli — a rather unsatisfactory 

 character, and one difficult to see. In tlie present paper several species 

 are located in Trichocladius. It is not the writer's intention to take 

 up at present the question of the generic relations of doubtfully lo- 

 cated American species of this group, but it is hoped that at some 

 future time either he or some other student of the group may have an 

 opportunity to devote to this problem the time requisite for its solu- 

 tion. 



The known larvae and pupae of this genus are included in the keys 

 to the early stages of the subfamily Chironomincc. 



Key to Illinois Species 



1. Males 2 



— Females 5 



2. Fore tarsi with long hairs; basal segment of abdomen and narrow 



posterior margins of other segments yellow 1. flavihnsis. 



— Fore tarsi without long hairs 3 



3. First, fourth, and seventh abdominal segments yellow, remainder 



hlaek 2. trifasciatus. 



— At most but two abdominal segments entirely yellow 4 



-4. First and fourth abdominal segments yellow 3. hicinctus. 



— First segment largely and posterior margins of other segments nar- 



rowly yellow 4. sylvestris. 



5. Abdomen with first, fourth, and seventh segments yellow 



2. trifasciatus. 



— Abdomen with at most 2 segments entirely yellow 6 



6. Fore tarsi blaek, seeond joint and basal half of third yellow 



5. slossonw. 



— Fore tarsi unieolorous, blaek or brown 7 



7. Abdomen with first and fourth segments yellow 3. hicinctus. 



— Abdomen with narrow yellow posterior margins to segments, the 



basal segment broadly yellowish 1, flavihasis. 



I. Cricotopus elavibasis, n. sp. 



Male. — Yellow, shining. Head yellow, antennae fuscous, scape 

 black, plumes fuscous, paler apically ; palpi brown. Mesonotum with 



