1919.] NATURAL SCIENCES OF PHILADELPHIA. 73 



overlapping, area of distribution. From alacris, neo-mexicana 

 can be chiefly distinguished by the more semi-elliptical fastigium, 

 the sides of which converge in well-rounded curves, with the apex 

 very broadly, or at least obtusely, rounded, and in the subgenital 

 plate of the male being but moderately produced. The coloration 

 of the two species is usually distinctive, but not invariably so. 

 Very rarely, in the male sex, the fastigium will be unusually angu- 

 late in neo-mexicana, so much so that the separation of such speci- 

 mens from alacris is difficult. The male subgenital plate will be 

 found, however, to furnish a good index of the specific position 

 of the specimen, almost invariably supported by coloration fea- 

 tures. In their habitats the two species frequent radically different 

 environments, neo-mexicana being invariably campestrian and 

 alacris a species of woodland cover or recently cleared timber 

 land, which still retains its low growth or has grown up in wood- 

 land scrub. 



Tyjje. — 9 ; Northeastern New Mexico. [United States National 

 Museum, Type No. 1030.] 



This specimen has been dried from alcohol, but the species 

 has been correctly determined by all subsequent authors excepting 

 Stal, who probably was unacquainted with the description of 

 neo-mexicana. Measurements of the type are given below. 



Morphological Notes. — The principal points of morphological 

 variation are: general form; horizontal angle of fastigium and 

 angle of face. The general form is slender, but the series from 

 the Baboquivari Mountains, Arizona, shows an average more 

 robust form in both sexes. This is not an absolute condition, 

 however, but an average, as several specimens, representing both 

 sexes, from that locality are but little different from numerous 

 individuals taken from the entire series of the species. This 

 greater bulk applies to depth as well as breadth, and is correlated 

 with a generally less strongly declivent face and a broader fastigial 

 angle. The form of the fastigium varies in both sexes to at least 

 as decided a degree as in the other species of the genus, yet being, 

 as a whole, shorter, broader and blunter in the Baboquivari Moun- 

 tains specimens than in the others. There is, however, appreciable 

 variation in these features in even the limited series from that 

 locality, and in series such as those from Cisco, Marathon and 

 Dallas, Texas, and Syracuse, Kansas, the range of variation is 

 very pronounced in each, the extremely narrow, most acute type 



