256 UNIVERSITY OF COLORADO STUDIES 



4. Hair on second abdominal segment all black (Boulder, May 21, 1906, G. Hite) 



acerba Cresson 

 Hair on second abdominal segment partly light; fifth segment with a light band 

 (Boulder, fls. Phacelia, June 4, W. P. Ckll.) . . edwardsii vagabunda Ckll. 

 The female acerba has not been taken in our region. It seems possible that the male 

 assigned to acerba is after all a variety of T. edwardsii. The specimen of acerba 

 taken by Mr. Hite has the peculiarity of possessing only two submarginal cells 

 on both sides. This, if constant, would take it out of true Tetralonia, and place 

 it in the old-world genus Eucera. 



DIADASIA Patton 

 Hind spur of hind tibia strongly bent at end in female; basal joint of hind tarsus 

 ending in a long process in male (Boulder, Aug. 5, fls. Opuntia) australis Cresson 



EMPHOROPSIS Ashmead 

 Female with a patch of black hair in middle of thorax, and outer side of hind 

 tibiae with orange hair; male with face-marks white (Boulder, fls. Ribes; Mrs. 

 Bennett) johnsoni Ckll. 



ANTHOPHORA Latreille 

 Abdomen with white bands not due to hair (Boulder, fls. Psoralea and Solanum 



rostratum) smithii Cresson 



Abdomen without such bands i • 



1. Thorax above with black and pale hair intermixed, giving a gray effect; middle 

 tarsus of male with copious red hair (Boulder, fls. Ribes and Viola) simillima Cresson 

 Thorax above without black hair intermixed 2. 



2. Abdomen covered with grayish or fulvous hair; large species (Boulder, fls. Carduus, 



July 29, Ckll.) occidentalis Cresson 



Thorax and abdomen with bright fox-red hair, but apex of abdomen with black 

 (Ward, fls. Gilia, South Boulder Canyon, fls. white aster, Aug. 9, W. P. Ckll.) 



neomezicana Ckll. 

 Thorax and first abdominal segment with dense fulvous hair; rest of abdomen 

 black, with distinct narrow hair bands in male, and vestiges of bands in female 

 (Boulder) montana Cresson 



CERATINA LatreiUe 

 Small; apical portion of male abdomen narrow; hind femora of male triangular; 

 female with a light mark on clypeus (Boulder, fls. Calochortus and Phacelia) 



nanula Ckll. 

 Larger, more robust, female 7 to 8 mm. long; apex of male abdomen broadly 

 triangvilar (Boulder, fls. Platycodon, Calochortus, Argemone, Phacelia) 



neomezicana Ckll. 



PSITHYRUS Lepeletier 

 Large; BombusAike; hair of thorax above fulvous, broadly black between the 

 wings; abdomen shining black, with some light yellow hair at sides toward apex 

 (Ward, fls. Lupinus) insularis Smith 



