24C UNIVERSITY OF COLORADO STUDIES 



3. Larger, antennae of male long, the joints of flagellum much longer than broad 



(Boulder Canyon, June) hydrophiltis Ckll.^ 



Smaller antennae of male much shorter, the joints of the flagellum short; punctures 

 of abdomen very strong (Boulder, fis. Campanula) 



brevicomis Rob., form opuntise Ckll. 



4. Comparatively large and robust, with the hair of the thorax above yellowish or 

 ochraceous; second submarginal cell very broad (Ward, July, fls. Frasera). 



kincaidii Ckll. 

 Smaller, with the hair pallid 5. 



5. Female; hair very pale, the abdomen with broad feltlike white apical hair-bands, 

 and white hair on basal part of segments; malar space twice as broad as long 



(Ward, July, fls. Phacelia) phacelise Ckll. 



Males, with long antennae; hair of face white (male kincaidii, if run to here, is 



separated by ochreous hair of face) 6. 



Males, wath antennae of the short type 7- 



6. Larger; hair of head and thorax yellowish-white (Florissant) sieverti Ckll.* 

 Smaller; hair of head and thorax clear white (Boulder) . salicicola geranii Ckll. 



7. Larger; hair of thorax above a little yellowish (Florissant) . florissantia Ckll.* 

 Smaller; hair of thorax above not yellowish (Florissant) . . polemonii Ckll.* 

 I had described C. opuntia as a distinct species, but Mr. Swenk gives good reasons 

 for supposing it only a form of brevicomis. He has the latter from as far west as 

 Sioux Co., Nebraska, and Missoula, Montana. 



The flowers of Petalostenwn in eastern Boulder County should be examined, with 

 the hope of finding C. aberrans Ckll. and C wilmatta Ckll. The latter has red legs. 



PROSOPIS Fabricius 



Face entirely black; size relatively large basalis Smith$ 



Face not entirely black i . 



1. Scape of antennae heart-shaped, one side light 2. 



Scape not heart-shaped, all dark 3. 



2. Larger; anterior wing over 5 mm basalis Smithy 



Smaller; anterior wing under 5 mm.; face markings cream-color. (Florissant) 



antennata Cress. 3* 



3. Females; clypeus entirely dark 4. 



Males; clj'peus light 5' 



4. Larger; anterior wing over 4 mm. (Boulder, May 1906, Grant LeVeque) 



varifrons Cress. 

 Smaller; anterior wing under 4 mm tuertonis Ckll. 



5. Lateral face marks curved above, receding from orbits (Florissant) tridentula Ckll.* 

 Lateral face-marks not curved above, or receding from orbits ... 6. 



6. Upper part of lateral face-marks very broad coloradensis Ckll. 



Upper part of lateral face-marks narrow and pointed (Boulder) universitatis Ckll. 

 P. basalis was found at Ward, at flowers of Drymocallis and Senecio. In South 

 Boulder Canyon, Aug. 9, 1906, my wife and I took two male coloradensis and 

 three female tuertonis visiting the same plant of Solidago. This would appear 

 to indicate that these are the sexes of one species, but the first abdominal segment 

 is much duller and more conspicuously punctured in coloradensis than in tuertonis. 



