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19 Second recurrent nervure joining second submarginal cell before its end; parasitic 

 bees, without scopa. 20 



Second recurrent nervure going beyond end of second submarginal cell. 



21 



20 Abdomen with the bands broken into widely separated spots; very small species 

 (Santa Fe, New Mexico). Chelynia permaculata Ckll. 

 Abdomen with the bands nearly entire, or several quite entire. 



Chelynia monticola Cresson and C. subemarginata Cresson 



2 1 Very small, about 7 mm. long or less, with bright yellow markings; no scopa (Santa Fe, 

 New Mexico). Stelis rudbeckiarum Ckll. 

 Large, more robust, females with a scopa. Dianthidium (10) 



22 Marginal cell extremely minute; very small parasitic bees. Neolarra 

 Marginal cell normal. 23 



23 Head and thorax metallic, blue or green. 24 

 Not metallic. 26 



24 Basal nervure strongly bent or arched; very small species; females with no ventral 

 scopa. Dialictus (n) 

 Basal nervure straight or little arched. 25 



25 Stigma well developed; marginal cell more pointed; females without ventral scopa 

 (only one species in our region, visiting Nothocalais and allies). Diandrena (12) 

 Stigma little developed; marginal cell more obtuse at end; females with a ventral 

 scopa on abdomen (many species). Osmia 1 (13) 



26 Third discoidal cell contracted above, the recurrent nervures joining the second sub- 

 marginal cell not very far apart; small bees. Phileremus (14) 

 Third discoidal cell not so formed. 27 



27 Marginal cell at apex very obtuse or subtruncate; small parasitic bees with hind 

 margins of abdominal segments reddish, and abdomen with pale or white spots of 

 appressed scale-like hairs. 28 



Marginal cell pointed. 29 



28 Abdominal spots white; abdomen reddish (Colorado Springs). 



Neopasites pulchellus Cresson 

 Abdominal spots dull; insect rather larger and much darker (Boulder, at flowers of 

 Grindelia, July 16, 1908, W. P. Cockerell). Neopasites heliopsis Rob. (15) 



. 29 Head and thorax with yellow or yellowish-white markings; small bees with very little 

 hair, the abdomen black without bands. Prosopis (16) 



Head and thorax without light tegumentary markings. 30 



30 Second submarginal cell quadrate, only moderately narrowed above; first recurrent 

 nervure meeting first transverso-cubital; stigma well developed; wings dusky; thorax 

 not hairy. Prosopis basalis Smith, female 



Second submarginal cell more elongate, more narrowed above; thorax hairy. 



31 



1 Chelynia pavonina Ckll., from Boulder, is like a bright metallic Osmia, without ventral scopa. Only 

 one specimen is known. 



The following species of Osmia were taken at Tolland in 1909 (Robbins): O. longula Cress., O. brevis 

 Cress., O. propinqua Cress., O. pentstemonis Ckll. 



