CHARLES W. METZ. 101 



6. Both ventral plates nude, (figs. 63 and 59) calviis, n. sp. 



Seventh ventral plate lacking basal lobe of wings ; eighth ventral 



plate short, stout, (figs 61, 62) nevadeiisis. 



Seventh ventral plate with small, ear-like membranous flaps, not 



apical, (figs. 55 and 67) asiiiiiius. 



Membranous flap apical, broad, basal lobe long narrow (fig. 57). 



polifolii. 

 Similar to poHfolii, but basal lobe short. 



lueg'alotis, wootoiii and coloradeiisis. 



KEY TO FEMALES. 

 No satisfactory characters for distinguishing all the fe- 

 males have yet been found. The following is intended to 

 aid in separating them into groups, which are treated sepa- 

 rately under their individual headings. 



Veiy large, enirely black basalis. 



Very small, face entirely dark cressoui group. 



Abdomen impunctate or nearly so, face marks short 1. 



Abdomen impunctate or nearly so, face marks long, extending above 



antennal sockets 2. 



Abdomen conspicuously punctured, lateral face marks long 3. 



Abdomen conspicuously punctured, lateral face marks short 4. 



1. Large, 7 mm. Yellow on collar and usually on clypeus, (fig. 135), 



thorax finely, densely punctured, Wes. U. S....COnspicua. 

 Similar but smaller, 4-5 mm., punctures of thorax sparse, tarsi dark, 



lateral areas of face narrow, (fig. 137) riidebeckia'. 



Similar but very small, tarsi yellow cressoni form mesilla?. 



Similar but collar and tarsi dark, very small cressoni group. 



Rather large, 6 mm., collar yellow, puncturation moderate, East 



United States modest us group. 



Large, stout, face marks very small, collar dark, (fig. 130). 



varifrous and episoopalis. 

 Collar yellow, lateral face marks mere strips, lateral areas broad, 



Wes. U. S., (fig. 117) coloradeusis. 



2. Face marks filling lateral areas, long, triangular, (figs. 138 and 139). 



zizite, episeopalis. 

 Collar yellow, puncturation of thorax exceeding coarse Ibssata. 



3. Collar yellow, lateral face marks continue broad to truncate apex 



far above antennal sockets asiiiimis, iiiegalotis. 



Lateral face marks narrow, long, abdomen very finely punctured, 

 (figs. 118, 122) wootoni, polifolii. 



4. Abdomen very finely punctured, biit closely so. 



iievadensis and cookii. 



TRANS. AM. ENT. SOC. , XXXVII. (13*) 



