NORTH AMERICAN BEES. 187 



Supra-clypeal mark broad but tapering above, like 



a bisbop's mitre . . . . • 22a. 



Supra-clypeal mark small and narrow . . . 23. 

 Supra-clypeal mark an elongated triangle . . triangularis. 



22a. Wings clear coguillettii. 



Wings more or less darkened . . • .22 b. 

 22//. Larger, scape witb only a light streak, face not 



much narrowed below episcopalis. 



Like the last, but smaller, scape all dark, face 



yellow, hind tibia? wholly yellow . . . illwocnsis. 



Smaller than episcopalis, half of scape light, face 



much narrowed below georgica. 



23. Lateral face-marks very broad ; face broad below . color aden sis. 

 Lateral face-marks narrow ; face much narrowed 



below ........ asinina. 



24. Lateral face-marks not tapering to upper end, but 



broadly truncate 25. 



Lateral face-marks tapering to upper end, pointed 

 or very narrowly truncate . . . . .27. 



25. Dorsal punctuation of 1st and 2nd abdominal seg- 



ments very distinct ; punctuation of mesothorax 

 relatively coarse ...... rugosvla. 



Dorsal punctuation of 1st and 2nd abdominal seg- 

 ments extremely fine or almost wanting . . 26. 



26. Markings bright lemon-yellow ; apex of supra- 



clypeal mark minutely notched .... zizia,. 



27. Dorsal punctuation of 1st abdominal segment in- 



distinct or wanting ...... modesta. 



Dorsal punctuation of 1st abdominal segment quite 

 distinct 28. 



28. Face-markings white or cream-colour, orbits strongly 



converging below ...... 29. 



Orbits little or not converging below . . . 28^. 

 28a. Face-markings buff ; large species, tubercles dark, 



wings fuliginous ...... suffusa. 



Face-markings bright lemon-yellow . . . citrinifrons. 

 Very like the last, rather smaller ; face-markings 



orange, lateral marks differently shaped . . pennsylvamca. 



29. Tegulas wholly dark wootoni. 



Tegulse with a light spot divergens. 



P. affinis, Smith, and P. modesta, Say. — Mr. Eobertson 

 formerly published the opinion that these were identical. I 

 found I had two species from the Eastern U. S., to which I 

 applied these names, and accordingly wrote him about the 

 matter. He replied that he also had arrived at the conclusion 

 that there were two species concerned, and shortly afterwards 

 he published the distinctive characters in Canad. Entom. May, 

 1896. His two species are the same as mine, but what he calls 

 ajjinis I had called modesta, and vice versa. He further declares 

 that Say's supposed male of modesta is really pygmaa, and 



