214 



and only prairie species, H. rugosus, and also those of H. lialde- 

 manii, show a wide variation from bright red to nearly white. 

 The variation is usually discontinuous, there being three or 

 four fairly distinct colors: red, pinkish, yellow, and yellowish 

 white. Our collections of rugosus in the Illinois State Labora- 

 tory of Natural History, mostly from the humid prairie of cen- 

 tral Illinois, were classed as red and yellow. There are 141 rugo- 

 sus in all, 37 red-winged and 104 yellow, the latter number in- 

 cluding 46 taken in 1905, of which 15 were clear yellow, and 31. 

 taken mostly on the drier southern Illinois soils, were pale 

 whitish yellow. Haldemanii from the sand region in 1905 were 

 22 red, 1 pinkish, and 9 yellow. Hippiscus inhere a I at us and 

 Psinidia fenestralis, normally red-wiuged in Illinois, are yellow- 

 winged in the West. The only species variable in wing color 

 and common in both the Illinois sand regions and on the humid 

 prairie are Hippiscus rugosus and Arphia xanthoptera, but I have 

 not at present a sufficient number of these from each locality 

 for comparison. 



The facts at hand warrant the conclusion that while the 

 species of a given locality, and even the individuals of a species, 

 may differ greatly among themselves in regard to wing color- 

 ation, the general tendency of arid climates to replace red with 

 yellow and, under certain circumstances, yellow with blue, is 

 too evident to be questioned. 



A very similar effect upon tibial coloration is even more ev- 

 ident, and I have taken especial pains to collect evidence on this 

 point. A notable series showing a direct influence of the blow- 

 sand environment — virtually equivalent to climatic influence— 

 upon species within a short distance of each other, is afforded 

 in the genus Melanoplus by nearly every active sand-dune ex- 

 amined by us. In the first place, on the least sandy areas in 

 the nearest level cultivated ground, the dominant MeJanophis 

 is femur-rubr 'um , always with bright coral-red hind tibi*. Sec- 

 ondly, on the drier and more sandy grassy ground of the base 

 or lower slope of the dune we find it replaced by M. atlanis and 

 M. minor. Atlanis is here unusually variable in tibial color. 

 Most frequently it is red, as in femur-rubrum; sometimes paler, 



