Studies of North American Bees 13 



Paratypes. — Type lot (No. 4859), i J*; type locality, June 15, 

 1913, on Zisia aurea (4920), i J*; do. (4952; C. H. Waldron, 

 coll.), I $; do., June 22, 191 3, on Zisia aurea (53 13. 5314), 2 J*; 

 do., June 17, 1914, on Zisia aurea (8078, 8079), 2 J*; do., on 

 Erigeron philadelphicus (8096), i J*; do., June 20, 1914, on 

 Erigeron philadelphicus (81 18), i J*; do., June 20, 1914, on 

 Zizia aurea (8122, 8123), 2 5. 



A member of the morrisoni group. Closest to A^. morrisoni 

 Cresson 5> but third antennal joint much shorter (equal to 4 in 

 morrisoni) , mesoscutellum distinctly bilobate (slightly so in mor- 

 risoni), basal half of tergite i black (red in morrisoni) , black 

 median mesoscutal stripe complete, and more red on propodeum 

 and venter. Close also to A'^. dilitcida Cresson 5, but third 

 antennal joint is shorter ("a little" shorter than 4 in dilucida), 

 the mesoscutellum is distinctly • bilobate ("slightly impressed 

 medially " in dilucida), the tegulae are punctured ("smooth and 

 shining " in dilucida) , the apical margins of tergites 1—4 are 

 reddish (fuscous in dilucida), the labrum, mandibles, clypeus and 

 supraclypeus are yellowish or yellowish red (these red in 

 dilucida), the mesoscutellar band is broken or lacking and the 

 median propodeal band is partly red. The short third antennal 

 joint distinguishes tricurta from N. morrisoni flageUaris Ckll. 

 and N. alpha Ckll. From N . maculiventer, just described, which 

 flies in the same locality two months later, tricurta differs at once 

 in the yellow instead of whitish abdominal maculations ; the $ is 

 further distinguished by the extended yellow marks on the head, 

 and the J* by very decidedly longer fourth antennal joint, yellow 

 collar and other color differences. 



Nomada (Heminomada) civilis Cresson, variety e. 



A female from Cannon Ball, North Dakota, April 15, 191 3, on 

 Salix (O. A. Stevens, No. 4330) represents another variation of 

 the plastic N. civilis. It is closest to the Sioux county, Nebraska, 

 $, but is just a little smaller (7.5 mm.) and differs further in 

 having the light markings of the face red (except for a small 

 yellow spot on the lower corners of the face and the yellow basal 

 border of the labrum), the flagellum clearer red, the supra- 



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