180 BULLETIN 190, UNITED STATES NATIONAL MUSEUM 



Male. — Thorax deep brown-black, conspicuously marked with pale 

 yellow in a broad lateral stripe on prothorax, a thin line edging the tegula 

 and a large round mark laterally on metathorax, which also is shaded 

 transversely with yellow. Abdomen mostly bright lemon yellow ; seg- 

 ment 1 black ; segment 2 black with the anterior edge yellow ; segment 3 

 yellow, posteriorly edged with black, 4 olive-brown, 5, 6, and 7 lemon 

 yellow, slightly or not touched with black on posterior edges. Wings with 

 costa, nervules, and margins olive-brown. Otherwise like typical tibialis. 



Female. — Stout and contrastingly marked with yellow and deep brown 

 or black. Abdomen with segment 1 black ; segment 2 black with a narrow 

 anterior yellow edge; segment 3 yellow, posteriorly with a narrow even 

 or sinuous black edge, which is broadest in the center ; segment 4 entirely 

 brown-black ; segments 5 and 6 yellow with a narrow black posterior edge ; 

 last segment yellow and sordid yellow at tip. Beneath, all segments 

 yellow, narrowly edged with black. Otherwise like the male. 



Distribution. — Rocky Mountain States ; western Kansas ; Alberta ; 

 Pacific coast, southern California to British Columbia. 



Type. — Female. In the United States National Museum. 



Remarks. — Hy. Edwards's description of Trochilium pacificum is based 

 on a female (Washington Territory). He had two specimens, stated 

 to be male and female, but both are females, the one from California 

 (Akhurst collection in United States National Museum) much faded and 

 abraded. In long well-preserved series the variety pacifica, which pre- 

 dominates in the West, can be separated readily by its contrastingly yel- 

 low and black coloration from the more somber typical fonn of tibialis 

 from the East and from the much darker variety melanoformis. The 

 varieties overlap somewhat and examples which are old, faded and abraded 

 are not always readily placed, as is indicated by the types of the earlier 

 authors. Taxonomic studies establish conclusively that there is only one 

 endemic species, Aegeria tibialis, in North America. 



The western range of the species is covered by many records in the 

 United States National Museum: Seward County, Kans., male, female, 

 July 1910 (F. X. Williams) ; Hall Valley, Colo., 9,000 feet, July (Oslar) ; 

 Cardiff, Colo., 8,000 feet, July 18, 1918, Veta Pass, Colo., 10,000 feet, 

 male, July 28, LaPlata Mountains, Colo., 10,000 feet, 2 females. Aspen 

 Forest, Colo., July 26, 1937 (Engelhardt) ; Colorado Springs, Colo., 4 

 males reared from Populus deltoides, June 7, 1915 (B. T. Harvey) ; 

 Denver, Colo., male type of minimum, Neumoegen CD. Bruce) : Salt Lake 

 City, Jordan River, Utah, June 1914, series reared from cottonwood, June 

 1914 (Engelhardt) ; Beaver County, Utah, 7,000 feet, long series, July 14, 

 1914 (Engelhardt) ; Deer Creek, Prove Canyon, Utah, female, July 21, 

 1916 (Tom Spaulding) ; Warner Ranch Sta., La Sal Mountains, Utah, 

 9,700 feet, male, July 27, 1936 (Klots), and female, 9,000 feet, July 22. 

 1936 (E. L. Chadwick) ; Pecos, N. Mex., female at light, June 23 (Cock- 



