112 bulletin: museum of comparative zoology. 



The males of the section of TrieHs can be separated as follows : — 



1. Legs black; abdomen black, with transverse yellow spots, usually 



connected . . . '. hermione. 



Legs mostly pale 2 



2. Abdomen with some fulvous or golden hair especially on sides at 



tip of the segments; fulvous hair between the antennae. 



tcrensis. 



Abdomen without fulvous or golden hair; white or gray, and 



black-haired 3 



3. Abdomen very slender, first segment very long; fore wing with 



apical dark cloud octomaculata. 



Abdomen less slender, first segment rather broad; no cloud in 



apical part of fore wing alcione. 



The females of the section Trielis can be separated as follows : — 



1. Legs largely yellow; basal joints of antennae rufous 3 



Legs brown or black, antennae all black 2 



2. Legs black, no golden pubescence; spots on abdomen transverse. 



hermione. 



Legs brown, pubescence partly rufous or golden; abdomen with 



large; rounded spots , . ..i pollenifera. 



3. Abdomen with black hair on margin of segments above, trans- 



verse frontal suture sinuate octomaculata. 



Abdomen with mostly or wholly fulvous hair on margins of 

 segments above; frontal suture not sinuate. xantiana. 



Trielis alcione, sp. nov. 



Type.— M. C. Z. 10,027. Washington: Lone Tree, Yakima River, 

 18 July, 1882; Big Bend, Yakima River, 19 July, 1882; Ainsworth, 

 20 July, 1882. Samuel Henshaw. Three specimens. 



cf Black; long, white-haired. Clypeus, pronotum above, scutel- 

 lum, postscutellum, six bands on abdomen above (basal three more 

 or less interrupted) and, apical bands on ventral segments, yellow. 

 Legs yellowish, femora, especially of the front pair, more or less black 

 at base. Margins of abdominal segments above with dark brown 

 hair; no fulvous hair. Sometimes a spot on the pleura and a median 

 one on the metanotum behind, are yellow. The hair is longer, and 

 more dense than allied forms; the abdominal spots are transverse, 

 not rounded behind. There is no dark cloud in the fore wing, and the 

 marginal cell is longer than in T. .rantiana, and the recurrent veins 



