484 



ments with a few widely spaced, weak, dark hairs, which become 

 more numerous, broader, and paler on apical two segments; no lat- 

 eral apical thorns on eighth segment; ventral surface of last segment 

 of female as in Figure 5, Plate XXXI. 



Imago; Female. — Green. Head yellowish green, last joint of an- 

 tennae and the palpi brown. Thorax colored as in festiviis except that 

 the black median line is not present. Abdomen greenish yellow, the dor- 

 sal surface brownish on basal half of each segment. Legs yellow; 

 mid and hind tibiae with a black apical comb; apices of first two 

 tarsal joints and the remaining joints on all legs brownish. Wings 

 clear, veins yellow, cross vein brownish. All hairs on body and legs 

 yellow. 



Antenna about half as long as thorax, basal joint slightly en- 

 larged, globose, apical joint slender, as long as the preceding two 

 joints combined; length of palpi about ecjual to that of antennae. 

 Thorax similar to that of festiviis. Abdomen in type in poor condi- 

 tion. Legs stout; hairs short; basal joint of fore tarsus more than 

 1.5 times as long as fore tibia (70: 43). Wings with cubitus forked 

 below the cross vein. 



Length, 5 mm. 



Type locality, Thompson's Lake, Havana, 111., May, 1914 (C. A. 

 Hart and J. R. Malloch). Reared from larvae taken by dredging in 

 eight and a half feet of water. Paratypes from Havana, May 4, 

 1895, flyii'ig over surface of Illinois River (C. A. Hart). 



There are very many examples of the larvae of this species in the 

 Laboratory collection which were taken by dredging in various parts 

 of the Illinois River during 1913. 



A larva which is similar to the one here described and also to 

 that of Chironomms sp. C (p. 529) is figured and described from 

 Lake Leman, in Switzerland, by ]\Ille. A. Zebrowska in her thesis* 

 presented for the degree of D. Sc. In this paper she refers to the 

 species as Orthocladiiis B, and no reference is made to the imago. 

 The peculiar labial plate of these species is so different from that of 

 any known species of Chironomus that I had in my preliminary work 

 simply designated them as "Genus?", and it was a surprise to me 

 when what appears to be a typical Chironomus much resembling 

 viridis emerged from the pupa described above. 



Tanytarsus Van der Wulp 



The larvae of species of this genus are not sufficiently well known 

 to warrant the use of any particular character for their generic sepa- 



*Recherehes siir les Larves de Chironomides du Lac Leman. Lausanne, 1914. 



