Studies of North Aiiicrican Bees 19 



Joint 3 of antennae shorter tlian 4; sides of propodeuni witliout peculiar 



appressetl sericeous pul)escence i 



1. Joint 3 of antennae less than one-third as long as 4; flagellum con- 

 spicuously denticulate beneath, especially on antennal joints 

 6-1 1 which arc very concave medially beneath and apically 

 produced into a prominent denticle ; antennae black above, 

 bright red beneath, scape in front yellow ; head and thorax 

 black, the clypeus, labrum, mandibles, lateral face mark^, 

 tubercles and spot beneath, and usually lines on collar and spots 

 on mesoscutellum, yellow ; abdomen black with broad yellow 

 bands more or less narrowed medially, the apical margins of 



• the segments reddish ; 7-8 mm taraxacclla 



I. Joint 3 of antennae distinctly more than one-third as long as 4; 

 flagellum not conspicuously denticulate beneath, though some- 

 times very feebly denticulate or sinuate beneath (e. g., parallela, 



bicrista) 2 



2. Joint 3 of antennae about one-half as long as 4 3 



2. Joint 3 of antennae distinctly over one-half as long as 4. from three- 

 fifths to four-fifths its length 11 



3. Abdomen deep black with little or no reddish color 4 



3. Abdomen mainly or largely reddish 5 



4. Maculations cream color ; apex at most but very feebly notched, some- 

 times subentirc ; only the four basal joints of flagellum above 

 black; basal nervure interstitial with transverso-medial on the 



basad side ; 6-7 mm pallidipicla 



4. Maculations bright lemon yellow; apex deeply bifid; flagellum wholly 

 black above; basal nervure much basad of transverso-medial; 



7 mm apriliua 



5. Mesoscutellum strongly bilobed 6 



5. Mesoscutellum not strongly bilobed, usually only feebly subl)ilol3ate. 



7 



6. Mesoscutellum acutely bilobed; black of face extending in a broad 



sutural line from antennal bases downward between the yellow 



lateral face marks and the yellow supraclypeal spot and upper 



clypeus ; tergites 5 and 6 without yellow bands ; 6-7 mm. 



bilobata 



6. Mesoscutellum more obtusely bilobed ; yellow lateral face marks not 



or not distinctly separated from the clypeus and supraclypeal 



spot by black sutural lines ; tergites 5 and 6 with complete or 



narrowly interrupted, though partially concealed, yellow bands 



on the extreme bases of the tergites ; 8 mm bicrista 



7. Abdomen paler red, the basal half of tergite i usually not black 

 right across, but usually with a broad medially interrupted 

 yellow band across the middle, this sometimes obscure or want- 



19 



