AMERICAN PILOSE FLIES AND BUMBLEBEES. 279 



variations which have analogous coloration to that of Volucella 

 bomb. var. rufomaculata of the facialis group and of the Rocky 

 Mountain region. 



5. Volucella bombylans arctica of the evecta group is similar in 

 coloration to the arctic bumblebee Bombus gelidus and to other 

 species. 



6. Volucella bombylans var. rufomaculata of the Rocky moun- 

 tains has a similar coloration to twelve different bumblebee 

 species which occur in the same region. The Asilid fly Dasyllis 

 fernaldi of the same zone has a corresponding coloration to V. 

 rufomaculata and to the twelve bumblebee species. 



7. Volucella bomb, facialis of the Pacific coast has analogous 

 color patterns to three bumblebee species of this zone. Volucella 

 bomb, facialis lateralis of the Canadian zone and V. bomb, evecta of 

 the eastern states have not been studied on account of absence of 

 data as to their distribution. 



I am greatly indebted to Dr. A. Sturtevant, Dr. Johnson and 

 Dr. Lutz, for the use of their collections of flies and of Bombus, 

 also for their help and advice in this work. 



LITERATURE. 

 C. W. Johnson. 



'16 The Volucella Bombylans group in America. Psyche, Vol. XXIII., No. 6. 

 '25 The North American Varieties of Volucella bombylans. Psyche, Vol. XXII., 



April 1925. 

 E. Gabritschevsky. 



'24 Farbenpolymorphismus und Vererbung mimeticher varietaten der Fliege V. 

 Bombylans und anderes Zweifliigler. Zeitschr. fur Induktive Abst. und 

 Vererbungslehre, Bd. XXXII., Vol. i. 2. 

 C. E. Keeler. 



'26 Recent work by Gabritschevsky on the Inheritance of Color Varieties in 

 Volucella Bombylans. Psyche (A Journal of Entomology), Vol. XXXIII., 

 No. i, February 1926. 



EXPLANATION OF PLATES I-IV. 



All figures represent flies in a schematized way. The upper square is the thorax; 

 the second one is the scutellum; the third is the abdomen. The dotted line between 

 the abdomens of different flies shows the segments of the insects. The head is not 

 drawn. In Plate I. the black color corresponds to the black pile, the white to 

 white hairs, the spotted parts are of a yellow coloration, and the vertical parallel 

 lines correspond to a cadmium orange tint in the flies. In all the other plates, (I. 

 (11-27) and III., IV.) the uncolored parts of the schemes correspond to different 

 tints of yellow (the exact color stands in the explanation of the plates; these colors 

 have been compared with Ridgway's Color Standards R. Ridgway, "Color 



