580 TERTIARY INSECTS OF NORTH AMERICA. 



Length of body, 3 mm ; of wing, 2.S mn> ; of fore femora, 0.68 mm ; of fore 

 tibiae, 0.6 mm ; of fore tarsi, l mm ; of middle tibiae, l mm ; of middle tarsi, 

 1.25 mm . 



Chagrin Valley, White River, Colorado. One specimen (W. Denton). 



CHIRONOMUS PATENS. 



PI. 5, Figs. 18, 19, 28. 



Chironomus patens Scndd., Bull. U. S. Geol. Geogr. Suiv. Terr., Ill, 744-745 (1877). 



A single specimen, very well preserved, represents a species which is 

 provisionally referred to Chironomus. Nearly all the parts are present, and 

 the neuration of one of the wings is nearly perfect, showing the structure of 

 Chironomidae, but differing apparently from any genus yet characterized. 

 The antennae are parted and bent, but apparently perfect ; they seem to be 

 fifteen-jointed, the joints square, the apical no larger than the others, and 

 all apparently furnished (as indicated at one point only) with a fringe of 

 profuse, exceedingly delicate hairs, as long as the joints. The body is slen- 

 der and the wings three times as long as broad ; the costal vein runs only 

 to the tip of the wing, and the margin beyond it is very faint ; the first lon- 

 gitudinal vein runs uninterruptedly to the middle of the apical fourth of the 

 wing ; the second longitudinal nearly to the tip ; the third longitudinal vein 

 takes its rise from the second in the middle of the basal half of the wing, 

 and parts widely from the second, leaving an unusual space devoid of neura- 

 tion next the apex of the wing ; the fourth arises from the third rather 

 abruptly a little beyond its base, and has close beneath it the remnant of a 

 vein or a fold in the wing; the next vein forks just beneath the origin of 

 the fourth longitudinal vein, and leaves beneath it, next the posterior mar- 

 gin, a broad space without veins ; the two basal cells are very short, and" 

 there appear to be no other transverse veins in the whole wing ; all the 

 veins are hirsute. The legs are long and slender, and covered with spinous 

 hairs arranged in exact longitudinal rows, giving the legs a striped appear- 

 ance under the microscope ; the femora are rather short, and the tibiae and 

 tarsi of very unequal length excepting on the hind legs ; the tibiae and all 

 the joints of the tarsi are furnished apically with small spurs. 



Length of body, 3 mm ; antennae, l mm ; wings, 2.1 mm ; fore femora, 

 0.5(?) nim ; middle femora, U.6 mm ; hind femora, 0.8'" m ; fore tibia?, 0.8""; 



