AET. 9 AMERICAN XYLOTINE SYRPHID-FLIES SHANNON" 27 



E". Abdomen with fourth tergite dark metallic green and without 



yellow spots on second tergite, or fourth tergite black and 



yellow spots present or absent on second tergite. 



F\ Upper pleural pile coarse and black; second tergite 



t without, third with, yellow spots ; arista a little longer 



than width of face naknek Hine. 



G\ Third antennal joint as long as broad 



naknek naknek, sensu stricto. 

 G' Third antennal joint longer than broad 



naknek atlantica, new variety. 

 F^ Pleural pile entirely pale. 



G^. Arista shorter than width of face. 

 H\ Second tergite with yellow spots. 



I\ Arista yellowish rainieri, new species. 



F. Arista black confusa, new species. 



H^ Abdomen without yellow spots ; face less than 

 twice the width of third joint_flavifrons Walker, 

 G". Arista longer than width of face. 



H\ Second and third tergites both with decided yel- 

 low markings. 

 I\ Face more or less yellowish ; apical cross vein 

 joining third vein acutely ; robust species 



{bivittata Lovett) lovetti Curran. 



l^ Face black ; distal portion of apical cross vein 

 forming right angle with third vein. 

 J\ Rather slender species ; male with distinct 



spur on trochanter ejuncida Say, 



P. Robust species; male with spur barely 

 suggested (Mexico) 



hrachygaster Williston. 

 H'''. Either the second or third tergites without yel- 

 low spots, or both. 

 I*. Metathoracic spiracle distinctly larger than 

 third antennal joint; robust species 



(western) harhata Loew. 



Il Metathoracic spiracle not larger than third 

 antennal joint ; rather slender species. 

 J\ Abdomen steel blue, hind margins of ter- 

 gites two and three opaque (Mexico) 



stenogaster Williston. 

 J'"". Abdomen not steel-blue. 



K^. Fourth tergite longer than broad ; 

 third antennal joint of female much 

 longer than width of lower, side face, 

 angiistiventris Loew. 

 IC Fourth tergite broader than long; 

 third joint slightly longer than 

 width of lower face. 



ejuncida, variety 

 elongata Williston. 



