Studies of North American Bees 63 



ever, have the clypeus provided with appressed, silky white hair. 

 The female sex is much less variable, and as that sex has never 

 been described the following diagnosis is appended: 



$. Length 9-10 mm. Red ; a spot about bases of antennae which sends 

 down curved lines in the upper clypeal sutures, an ocellar spot, cheeks 

 behind, prothorax except the yellow collar and sometimes a yellowish 

 suffusion on tubercles, a median line on mesoscutum, depressed sides of 

 mesoscutellum and all of metanotum except a short median red line, 

 line under wings, metapleura, sides of the propodeum as far as the 

 spiracles, median line on posterior face of propodeum, large spots on sides 

 of mesosternum, coxae behind, small spots at extreme base below of mid- 

 dle femora and a stripe on posterior face of hind femora, area at base 

 of first abdominal tergite and a U-shaped mark on the first abdominal 

 sternite, black. Antennae red, joint 3 about two-thirds as long as 4. Two 

 large yellow spots on the sides of the enclosure coalesce with two large 

 yellow areas on the sides of the propodeum to form a broad yellow band 

 down each side, involving most of the posterior face of the propodeum. 

 Lobes of mesoscutellum not prominent, usually yellow spotted. Legs, 

 except for the black markings noted, wholly red. Tegulae red. Wings 

 hyaline, moderately darkened along apical margin, the nervures and stigma 

 brownish red, the basal nervure interstitial with the transverso-medial or 

 nearly so. First abdominal tergite, except the irregularly margined black 

 area at base and the dusky band at the apex, wholly red, tergites 2-4 

 with uniformly broad, complete yellow bands, emarginate laterally on 

 posterior margin on 4 and 5. Venter red, sometimes with small yellow 

 spots on sternites 4 and 5. 



Allotype. — Lincoln, Lancaster county, Nebraska, May ii, 1901, 

 on Ribes gracile (M. A, Carriker), 5- 



In addition to the series of eight males from Nebraska men- 

 tioned above, there are two males from West Point, Nebraska, 

 collected in June (the above series was all taken in April and 

 May), one June 22 on Erigeron raiiiosiis and the other June 25 

 on Symphoricarpos occidentalis, which differ strikingly in having 

 the black of the head and thorax largely replaced by red. These 

 obviously represent a distinct late-flying variety of eli'odi, at 

 least, if they are not the males of a distinct but closely related 

 species, and may be distinguished as follows : 



c?. Length 7-8.5 mm. Structurally essentially like N. elrodi 3, but 

 face above level of antennae and extending down in the clypeal sutures 

 (sometimes involving supraclypeus), vertex except an ocellar patch (which 



63 



