226 NEW YORK STATE MUSEUM 



Pupa. Pale yellow, with yellowish brown thorax; length 3.5 

 to 4 mm. Thoracic respiratory tracheae are delicate, much 

 branched, and white in color. The second and third abdominal 

 segments (fig.3) each are marked with an anterior transverse row 

 of caudad (projecting short setae, the disk more or less covered 

 with smaller and more delicate ones, leaving a number of round 

 clear spaces. The fourth and fifth are like the third, the following 

 ones with fewer setae. The first is bare, the second has besides 

 those mentioned the usual transverse row of black, longitudinal 

 ridges. The anterior lateral margin of the anterior segments is 

 marked with a pale brown cloud, most easily seen in the empty 

 pupal skin. The lateral fin of the eighth abdominal segment has 

 the usual filaments, each fin terminating in a toothed process, deep 

 brown in color (fig.4). The caudal fin has the usual fringe of 

 matted hairs. 



Imago, male. Yellow; length 2 to 2l/ 2 mm. Head with pro- 

 boscis, palpi, and basal joint of antenna yellow ; antennal flagella 

 and sometimes tip of proboscis pale fuscous. Thorax with all 

 its parts pale yellow, the dorsuni with three deeper yellow stripes. 

 In some specimens the metanotum, parts of the pleura and the 

 pectus somewhat deeper yellow. Abdomen wholly pale yellow, 

 with whitish hairs; in living specimens the abdomen is some- 

 times pale yellowish green; genitalia (pl.32, fig.12) long and 

 slender and yellow in color; the claspers long, the superior lobes 

 blunt with curved spines, the inferior lobes very slender and with 

 an elongate apical seta each. Legs wholly pale yellow, and 

 excepting the first pair rather hairy. Tips of the tibiae with the 

 usual minute black combs. The fore femur is about one third 

 longer than its tibia, and the fore metatarsus is about 1% as 

 long. Wings hyaline, with a slight milky tinge, veins colorless; 

 venation as shown on pl.28, fig.20. Halteres white. 



Female. Like the male, but the antennae are yellow, apical 

 joints are fuscous. The abdomen has a faint suggestion of white 

 margins on the segments. In some specimens the dorsal stripes 

 are quite indistinct; in living specimens the thorax is sometimes 

 a greenish yellow and the abdomen bright green. This species 

 must not be confused with Tanytarsus e x i g u u s which 

 it closely resembles, but from which it may 'be distinguished by 

 its distinct radial veins and hairless wings. Ithaca, N. Y. 



42. Chironomus brevitibialis Zetterstedt 

 1850 Chironomus Zett Dipt. Scand. 9:3537, 59 

 1864 Chironomus Schiner. Fauna Austr. 2 : 606 

 1877 Chironomus V. d. Wulp. Dipt Neerl. p.261, 22 

 1898 Chironomus Lundb. Videnskab, Meddel. p.273, 51 



