WILLIAM G. DIETZ 117 



Head entirely yellow, proboscis short, frontal prolongation shining, remain- 

 der opaque, mouth parts and palpi concolorous, last joint of the latter longer 

 than the three preceding joints together. Antennae of moderate length, 

 basal joint yellow, joints two and three dark yellow, remainder yellowish- 

 brown, finely pubescent, segments cylindroidal, outer joints very attenuated, 

 all with a verticel of setaceous hairs at the base, much longer on the outer joints. 

 A fuscous patch above each eye; a large, fuscous, pentagonal, shining occipital 

 spot; underside of head and portion behind the eyes, pale yellow. 



Thorax yellowish-white, opaque. Praescutal stripes black, narrowly edged 

 with ferruginous, shining, the median stripe widened at its anterior end, grad- 

 ually narrowed posteriorly; the lateral stripes narrower, the anterior end 

 curved outward and ending in a large opaque spot. Scutum with oblique, 

 reddish stripes, infuscate anteriorly. Scutellum testaceous with blackish 

 median groove. Postnotum bone white on the sides, testaceous posteriorly 

 and a large brown patch anteriorly. Outer part of transverse and posterior 

 end of pleuro-dorsal suture black. Pleura bone white, lower part of sterno- 

 and pteropleura and greater part of mesopleura, ocher-yellow. Halteres dull 

 yellowish-white, knob fuscous, paler at tip. Wings hyaline with a faint, gray- 

 ish tint, stigma brown, basal section of vein R 4 and 5 and cross vein R-M infus- 

 cated, apex infuscated, cell M 1 with very short petiole. Rs short, slightly 

 curved, oblique; Cu and crossvein M-Cu before fork of M; Sc ends opposite 

 of origin of Rs; Sc 1 present. 



Abdomen ocher-yellow, extreme base of first tergite blackish, second tergite 

 with two large, irregular, brown patches, tergites. three to seven tinged with 

 yellowish-fuscous, the seventh black posteriorly — remainder of abdomen want- 

 ing — lateral edges of tergites tinged with fuscous. 



Holotype: 9 ; Aweme, Manitoba, Canada. August 7, 1913. 

 (E. Criddle.) 



From P. virescens, incurva and excelsior, the other three species 

 in which the thoracic stripes are black, the lateral stripes curved 

 outward and ending in an opaque, black spot, the present species 

 differs from virescens in the shining, occipital spot, and from 

 incurva and excelsior in the proboscis, mouthparts and palpi being 

 entirely yellow. 



Pachyrhina snowii alternata subsp. n. 



Differs from true P. snowii Doane by its narrow fuscous occipital stripe, 

 absence of spots on the vertex and the pale, ill-defined, yellowish-fuscous stigma. 

 The interrupted abdominal stripes, with the exception of the dorsal stripe of 

 snowii, are represented by rows of spots or dashes. 



Holotype: d"; Northwestern Colorado. July 20, 1911. (E. J. 

 Oslar.) 



Paratype: cf ; Platte Canyon, Colorado. August 19, 1915. 

 (E. J. Oslar.) 



TRANS. AM. ENT. SOC, XLIV. 



