l6o UNIVERSITY OF COLORADO STUDIES 



the wing often pale and contrasting, and the serrations of the outer edge 

 of the band on the hind wing strongly marked. The size is not too 

 great for N. ridingsii. A closer study of the material confirms the 

 original reference to N. ridingsii, but at the same time suggests that 

 further collections of Neominois will yield facts of great interest from an 

 evolutional standpoint. 



The true Neominois ridingsii is an insect of the front range in Colo- 

 rado, ascending to .9000 ft. at Gem Lake, Estes Park (Gillette). It is 

 common in open grassy places at 8,000 ft. It descends, however, to the 

 plains at the base of the mountains, near Denver (Mead) and elsewhere. 

 It goes northward as far as Manitoba. 



Neominois dionysius occupies the Great Basin, and was described 

 from the Juniper Mountains, Arizona, and Mount Trumbull, Utah, 

 places not very far apart. It is a larger, gayer, insect, with the ocelli 

 on the front wings very large, and the serrations of the band of the hind 

 wings very marked. The male expands 48-51 mm., the female 55-58^. 

 As might be expected, it occurs also in western Colorado, where it has 

 been obtained by Bruce. On the other side of the Great Basin, in 

 Nevada, there is found a butterfly which Edwards distinguished in 1870 

 by the name streichii, but which is now placed in all catalogues as a 

 synonym of N. ridingsii. This insect is larger than the Colorado 

 form, but has in general the characters of ridingsii, not of dionysius. 



Finally, we have a record' of N. dionysius from the eastern plains, 

 in Sioux Co., Nebraska. 



In all this we appear to have a very clear and interesting case of 

 response to climatic conditions, and probably of the independent devel- 

 opment of similar types under similar environments. Mead remarks 

 that the color of the butterflies, as seen near Denver, harmonizes excel- 

 lently with that of the dry herbage among which they rest, and renders 

 them difficult of detection. It would be of great interest to secure full 

 series from different altitudes and regions, with particulars concerning 

 their surroundings, and see whether several minor races could not be 

 distinguished. It seems probable that the Nebraska '^dionysius" is 

 derived from ridingsii, not from the genuine dionysius of the Great 



» Cf. Skdjner, Syn. Cat. N. A. Rhopalocera, Suppl. No. i, p. 114. 



