112 HYMENOPTERA. 



(fig. 89); scape with irregular stripe in front. Tubercles, anterior 

 tibiffi, and tarsi yellow ; two yellow spots on collar, sometimes wanting. 



Genif alia. —Armature and seventh ventral plate similar to those of 

 P. cressofii, but larger, (figs. 16, 37) ; eighth ventral plate quite dis- 

 tinct, having the apical pedicel narrow, terminating in two short, mem- 

 branous lobes, each with a horn-like chitinous rod mesad, (fig. 50). 



Female. — Quite similar to same sex of P. cressoni, not always dis- 

 tinguishable from that species, but typical forms larger, with consi- 

 derable yellow on collar and clypeus, (fig. 137). 



Form DIGITATUS. 



Male. — Similar to typical form, but thorax wholly dark, and upper 

 processes of lateral face marks finger-like, without terminal enlarge- 

 ments ; scape dark, not dilated. 



Female. — Indistinguishable from typical form. 



Variety bakeri. 



il/a/^.— Differs from typical form in having scape swollen, strongly 

 concave exteriorly, the entire front and concave portion being yellow ; 

 upper processes of lateral face marks long, narrow at base, following 

 outline of antennal sockets, ending in a large, round swollen apex, 

 (fig. 88 shows the style of lateral face marks, although it is from 

 another form). 



Female. — Indistinguishable from typical form. 



Habitat. — Apparently not restricted in the United States, 

 I have specimens from Colo., Nev., N. M., Ariz., Calif., Ore,, 

 Tex., Alab,, N. J., Cana., etc., at various altitudes. Judg- 

 ing from the material at hand, and the records of others, it 

 is probably much more common in the Rocky Mountain States 

 than eastward. 



Specimens examined : about 150. 



This species is a very near relative of P. cresso7ii which it 

 resembles in both sexes. The females of the two, as is 

 usual with such close allies, are indistinguishable, except in 

 the typical forms. The males, altho usually quite distinct, 

 sometimes resembles those of P. cressoni in face marks and 

 have to be separated by genital characters. In color, size 

 and sculpture, this species varies much as does the other, and 

 most of the discussion given under that will apply here. 

 Usually both sexes have yellow on the collar, but numerous 

 specimens lack it. The face marks of the males before me 



