Studies of North American Bees 91 



I. Size largest, 7-10 mm., usually about 9 mm. long; abdomen black 

 or blackish, the apical margins of the tergites suffused with red, 

 tergites 2-6 with yellow bands, usually complete, that on i 

 sometimes narrowly interrupted medially by a red line, those 

 on 5 and 6 sometimes broken into spots, i usually with small 

 lateral spots which are usually distinct but sometimes wanting; 

 mesoscutellum and metanotum red ; antennae red beneath, the 

 scape yellow, above mostly black except the last six joints which 

 are red bella 



I. Size medium, 6-8 mm., usually about 7.5 mm. long; abdomen 

 blackish becoming more or less suffused with red on the apical 

 margins of the tergites, tergites 2-6 tj^pically with complete or 

 narrowly medially interrupted yellow bands, those on 3-6 sub- 

 basal and frequently concealed when the tergites are much re- 

 tracted, sometimes wholly lacking on 4 and 5, i frequently with 

 large yellow spots or a band ; mesoscutellum black, black spot- 

 ted with yellow or red or wholly red, metanotum sometimes more 

 or less red ; antennae red beneath, the scape usually yellow but 

 sometimes red, above mostly black or blackish, this suffusion 

 extending nearly to the tip lepida 



I. Size smallest, 5.5-7 mm., usually about 6 mm. long; abdomen mostly 

 red, base of tergite i black and more or less distinct dark 

 median or subapical bands may occur on 1-5, these usually 

 narrow but sometimes extended to infuscate most of the apical 

 tergites, tergites 2-3 always with large distinct yellow lateral 

 spots, these occasionally extended inwardly to form more or 

 less narrowly interrupted or occasionally complete bands, in 

 which case 3-4 have more or less obvious lateral yellow spots 

 or bands, tergite 6 often with a yellow band or two yellow spots, 

 tergite i rarely with small lateral spots ; mesoscutellum usually 

 wholly red, sometimes black with red spots on the lobes, metano- 

 tum usually red also, sometimes black ; antennae beneath clear 

 yellowish red, the scape in front often distinctly yellowish, 

 above suffused with black more or less on the first seven joints, 



the last six joints clear red carolinae 



(The male of siouxensis is unknown or unrecognized.) 



Nomada (Gnathias) bella Cresson. 



1863. Nomada bella Cresson, Proc. Ent. Soc. Phil, II, pp. 287-88, c?. 

 1863. Nomada maciilaia Cresson, ihid., pp. 303-04, $ (c??). 



1902. Nomada bella Robertson, Ent. Nezvs, XIII, p. 80. 



1903. Gnathias bella Robertson, Can. Ent., XXXV, p. 172, ($. 

 1903. Gnathias maciilata Robertson, ibid., ?. 



1903. Nomada bella Cockerell, Proc. Acad. Nat. Sci. Phil., p. 601, 5 c^. 



91 



