216 



with its moister atmosphere, at the eastward, and for the more 

 arid western regions, will be of interest. 



Femur-rubrum and atlanis are common on the humid prai- 

 rie of Illinois. The tibiae of the former are always red there, 

 as in the sand region ; those of the latter, as shown by a large 

 number of specimens, are about ninety percent red — the rest 

 being green— instead of only two thirds red as in the sand re- 

 gion. Blatchley ('03) says of angustijpennis in the Lake Mich- 

 igan sand region, that at least one third had red tibiae, the rest 

 blue. In a series of 64 specimens, 33 males and 31 females, 

 taken by me near Waukegan, exactly one half have red tibiae. 

 This is very significant, since red tibiae were seen in only two 

 out of 125 of the same species in our western Illinois sand re- 

 gions. The tibiae of minor, according to Blatchley, are usually 

 pale blue, pinkish at tip, sometimes red or dull yellow. 



Of these four species in regions to the westward I have 

 found the following records. McNeill ('99) found one female 

 femur-rubrum in October in southwest Arkansas with green 

 hind tibiae. In Texas 1 have recorded ('06) two such occur- 

 rences among only a few specimens seen in the early part of 

 the winter. Scudder ( '97 ) says the hind tibiae are normally red, 

 occasionally more or less tinged with yellowish, very rarely 

 pale green with a yellowish tinge. Examples with greenish 

 tibiae are recorded by him from the alpine region of the White 

 Mountains, and from Massachusetts, Utah, Texas, and Mexico. 

 The Massachusetts localities appear to be sandy districts. Gil- 

 lette ('04) notes that the uniform fuscous-brown of this species 

 in the East becomes in Colorado variably yellow-brown or with 

 bluish tints, in the latter case the tibiae also often bluish. 



As to atlanis, Scudder ( '97) says the tibiae are normally 

 rather bright red, not infrequently pale red, green, or yellow, 

 or even dark blue. According to him, examples from the arid 

 West are decidedly paler and more ashy, also those from sandy 

 localities such as the seashore. He records green tibiae in New 

 Hampshire and Massachusetts at the East, and in Montana. 

 Wyoming, Dakota, Colorado, Nebraska, and Missouri at the 

 West; also blue tibiae in Iowa, Colorado, Utah, and Texas; but 



