Robertson — North American Bees. 325 



Agapostemon Guerin. 



Widely distributed over the United States are four species 

 of this genus, whose females have been described in such a 

 way that it is not difficult to determine them, but whose 

 males have been so inadequately described and identified that 

 the names, even when having distinct priority, can hardly be 

 regarded as available. It is proposed in this paper to adopt 

 the names of the females, and to indicate as fully as possible 

 the characters which distinguish the species. 



Agapostemon viridulus F. occurs from Canada to Georgia 

 and west to Washington, Utah and Texas. 



Agapostemon radiatus Say occurs from Canada to Georgia 

 and west to Dakota, Kansas and Texas. 



Agapostemon splendens Lep. ranges from Canada to Florida 

 and west to Nebraska and Texas. 



Agapostemon texanus Cress, is distributed from Massa- 

 chusetts to Georgia and west to Vancouver and Southern 

 California. 



The males are much alike, especially in their ornaments, and 

 these common characters are almost the only ones mentioned in 

 the descriptions, whence the difficulty in determining to which 

 one of the four ppecies the descriptions relate. I shall now 

 indicate the common characters of these males of Agaposte- 

 mony and in the descriptions under synonyms shall only men- 

 tion those which are important in making the distinctions 

 between the species. 



Head and thorax golden green; mandibles except tips, lab- 

 rum, clypeus anteriorly and scape in front yellow ; flagelium 

 fulvous beneath, joints submoniliform ; head and thoraxdensely 

 punctured ; nervures, stigma and tegulae testaceous, the latter 

 with a yellow spot in front, legs yellow, middle and hind 

 tibiae exteriorly, and hind femora at tip above marked with 

 black ; abdomen black, middle of first and basal margins of 

 segments 2-5 with yellow fasciae. 



In the males of A. viridulus and A. texanus the abdomen 

 has only five fasciae, while in A. radiatus and A. splendens it 

 has six. But the apical segments are often retracted so that 

 the sixth fascia is usually concealed, and sometimes also the 



