292 PROCEEDINGS OF THE ACADEMY OF [April, 



separated from muticus as found in the Guianas, 155 by the head being- 

 marked with four pale longitudinal lines and the caudal metatarsus 

 being shorter and broader with dorsal margin more distinctly arcuate. 

 The head marking appears often, though usually not strongly defined, 

 being particularly apparent in immature examples or adults of pale 

 general coloration, over nearly the entire distribution of the species. 156 

 Various series show that the metatarsal length and heaviness is 

 extremely variable in the species, though often uniform in large 

 series from the same general region. 157 Variations in tegminal and 

 wing length, and in the caudal metatarsus, are principally the cause 

 of the above synonymy, though other variations, decidedly puzzling 

 without large series being available for comparison, also occur. 



Within the boundaries of the United States the species shows 

 appreciable differences from material from the Guianas; these 

 differences due, in our opinion, to an adaptation to the differences in 

 environment and climate, but, considering the plasticity of the 

 species, neither sufficiently constant or well marked to warrant the 

 recognition of a geographic race. The most noteworthy of these are : 

 the somewhat more evenly rounded and protuberant occiput; slightly 

 weaker inter-antennal protuberance; slightly less prominent eyes: 

 more nearly quadrate dorsum of the pronotum, with caudal margin 

 straight or weakly convex (never weakly bisinuate as in typical 

 muticus); color frequently decidedly paler, with the pale marking 

 at the ventro-cephalic angle of the lateral lobes of the pronotum 

 (usually conspicuous in typical muticus) subobsolete. 



Along the Atlantic coast of the United States the species is usually 

 found to have the metatarsus very slightly longer than is typical, 

 but of similar proportions; specimens from Alabama westward, 

 however, have the metatarsus distinctly shorter and slightly 

 heavier. 



The examples from Victoria, Texas, have the occiput more dis- 

 tinctly striped than in any but Argentinian material before us. 

 Great variation in intensity of coloration is shown in the series here 

 recorded; although these specimens average decidedly paler than 

 tropical material of the species, the four adults from Hebardville, 



155 A large series now before us from British Guiana appears to be in every way 

 typical. 



156 This marking being less apparent in adults of intensive coloration, it is not 

 surprising to find few of these in tropical series which are usually dark in general 

 coloration. 



157 We are able to ascertain this fact from very large series now before us from 

 the West Indies, Central and South America. 



