214 



and only prairie species, H. riKjotiaa, aud also those of //. hahle- 

 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 nn/osiis in the Illinois State Labora- 

 toi"y of Natural History, mostly from the humid prairie of cen- 

 tral Illinois, were classed as red and yellow. There are 141 ni(/o- 

 .^7^s 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. Haldeiinuui from the sand region in 1905 were 

 22 red, 1 pinkish, and 9 yellow, llippiscus ttihcrruJafns and 

 Fsinidia fcHestralk, normally red-winged 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 Hippigciit; n((/osns and Arplila .raidhopfcra, but I have 

 not at present a sufhcient 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 que.stioned. 



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 ^Iclanoplii^ 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 Mflanoplns 

 iii fan in--nihiinii, 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. at Id ii is aud 

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

 Most frequently it is red, as in fei)nir-nihnnii\ sometimes paler, 



