81 



these colours in virginiana replace the griseous of infuscata on the 

 whole of the head, pronotum, thoracic pleuras and hind femora and on 

 the greater portion of the costo-basal half of the tegmina, besides 

 forming spots at and beyond the middle of their front border, which 

 are pale in infuscata ; these ditFerences are mainly, but by no means 

 exclusively sexual ; for out of about one hundred and fifty specimens 

 in my collection, 84 per cent, of the males are infuscata, and 77 per 

 cent, of the females are virginiana ; males of virginiana are there- 

 fore perhaps rarer than females of infuscata. These proportions 

 are nearly the same in all districts, judging from a comparison of 

 considerable material from New England, Florida and Texas. 



Specimens from these three regions, however, difier strikingly from 

 each other, so that I Avas at first inclined to consider them as distinct 

 species. As, however, a perfectly parallel dimorphism runs through 

 them all, and certain parts of the organization of these insects present 

 some degree of variability within each district, one is forced to the 

 conclusion that they must be identical. The great disparity in the 

 length of the antennte between New England and Texan specimens 

 is most remarkable, but as individuals from such northern localities as 

 Norway, Me., and the White ]\Its., N. H., show an exaggerated ab- 

 breviation, we can hardly doubt that a southern habitat is favorable 

 to length of antennae. 



The differences between specimens from these several regions will 

 best be presented in a tabular form : — 



Antennae 



Fastigium of the 

 vertex 



Pale spots in teg- 

 mina of male 

 Cloudiness of wings 



New England. 



(^ about three- 

 fourths the length 

 of tile hind tibia;. 



$ from one half to 

 neaily three-fifths 

 the length of the 

 hind tibias. 

 distinctly longer 

 than bread, with 

 elevated bound- 

 ing ridges, nar- 

 rower at tlie ex- 

 tremity than in 

 southern speci- 

 mens. 



obscure, sometimes 



obsolete, 

 faint, and confined 



to the distal half 



of the wing. 



Texas. 



cf about seven- 

 eighths the length 

 of the hind tibia;. 



2 scarcely two- 

 tliirds the length 

 of the hind tibia;. 



distinctly longer 

 thau broad, with 

 rather slightly el- 

 evated bounding 

 ridges. 



distinct. 



rather intense, and 

 conhned to the 

 distal half of the 

 wing, and also to 

 the lower half, 

 the uj)per portion 

 being uiuisually 

 clear. 



Florida. 



cf about three- 

 fourths tlie length 

 of the hind tibia;. 



? three-fifths the 

 length of the hind 

 tibhe. 



of equal length 

 and breadth, with 

 rather slightly el- 

 evated bounding 

 ridges. 



distinct. 



moderately intense 

 and diffused, of- 

 ten infringing 

 considerably' on 

 the ba^al half of 

 the wing. 



