Studies of North American Bees 69 



]\Iesoscutum black ; legs yellow, the coxae, femora above and 

 behind, and a stripe on four posterior tibiae behind, black; 

 flagellum red, black at the end; mesoscutelhnn wholly 

 yellow citrina Cresson 



Of the several forms above tabulated, flavotnarginata seems to be 

 closest related to A^. semirufiila Ckll. {Bull. 94, Colorado Exp. 

 Sta., pp. 80-81, $), from Colorado, from which it dififers chiefly 

 in the possession of the yellow suprategular stripe, more black on 

 mesoscutum, chiefly yellow legs, small blackish centers to the red 

 lower pleural spot, basal nervure interstitial with transverso- 

 medial, etc. From ^V. rufiila Ckll., from Idaho {Proc. Acad. 

 Nat. Sci. Phil., 1903, p. 586, 5), the apically blackened flagellum, 

 three black lines on mesoscutum and wholly yellow mesoscutellum 

 are diagnostic characters. From typical A^. citrina Cress. ( Trans. 

 Am. Ent. Soc, VII, pp. 79-80, 5), of California to Washington, 

 it differs in having the yellow suprategular stripe, in the reddish 

 suffusion of the coxae, trochanters and femora behind, in the 

 lack of black on the middle femora and the posterior face of 

 middle tibiae, in having the apical margin of tergite i and most 

 of sternite i reddish, etc. In addition to the shorter third 

 antennal joint, it differs from the other forms in this group as 

 follows: From typical perivincta, from Colorado, in its slightly 

 smaller size, more extensively red vertex, two broad reddish 

 mesoscutal bands, mostly red lower pleural spot, chiefly yellow 

 legs which are merely suffused with reddish on the coxae, 

 trochanters and femora behind, the wholly yellow clypeus, yellow 

 bases of mandibles, mostly yellow posterior orbits, reddish apical 

 margins of tergites 1-4 and the red first abdominal sternite which 

 is relieved only by a trilobate yellow median mark. From peri- 

 vincta var. b, also from Colorado, the type of which the writer 

 examined in the U. S. National Museum, in smaller size (the 

 Colorado insect is 11 mm. long), in having the apical margins 

 of tergites 1—4 reddish and of variable width (very even, narrow 

 and blackish in the Colorado specimen), in having the hind 

 femora and tibiae with merely a narrow stripe behind (largely 

 black in the Colorado specimen), in having small blackish centers 

 to the red lower pleural patches (these all red in the Colorado 



69 



