1913.] NATURAL SCIENCES OF PHILADELPHIA. HI 



On comparison with a series of vaga from a number of localities, 

 the Clarion Island series is seen to be practically identical except 

 for the short tegmina and wings. In view of the uniformity of 

 this character in all of the five specimens, we deem it best to con- 

 sider the Clarion Island form at least a geographic subspecies, 

 limited as far as known to Clarion Island. It is quite curious 

 to note that typical vaga is found on Guadelupe Island off the west 

 coast of Lower California, in fact, that island was one of the 

 original localities, and from the measurements given by Scudder 

 it will be seen that the specimens were of the normal long-winged 

 type. The distance of Guadelupe Island from the nearest portion 

 of the mainland, i.e., Lower California, is about one hundred and 

 seventy miles, while Clarion Island is about four hundred and thirty- 

 five miles from Cape San Lucas, the nearest mainland point. The 

 difference in chstance may possibly account for the difference in 

 wing length by the hypothesis that vaga regularly flies to and fro 

 between Guadelupe Island and the mainland, and the resident 

 brood is recruited by new arrivals and produces, through the in- 

 fluence of new blood and the presence thereby of a comparatively 

 active migratory influence, generations in which the wings are very 

 powerful. On the other hand. Clarion Island was probably colon- 

 ized by stray migrants, and from these has evolved a short-winged 

 type through isolation and lack of use for the wings except in a 

 restricted area. While we are unaware of the presence of S. vaga 

 on the Revillagegedo Islands, the species, and possibly subspecies, 

 may occur there, the nearest one of the group, Roca Partida, being 

 one hundred and forty miles distant from Clarion Island. 



The measurements of the types of Schistocerca vaga hrevis are as 

 follows : 



d^ 9 



Length of body 30.5 mm. 43 mm. 



Length of pronotum 7 " 9.5 



Length of tegmen 24.5 " 33.5 



Length of caudal femur 19.2 " 24.5 " 



Schistocerca sequalis Scudder. 



1899. Schistocerca fequalh Scudder. Proc. Amer. Acad. Arts and Sci., 

 XXXIV, p. 458. [Demerara, British Guiana.] 



Caracas, Venezuela. (Dr. A. Ernst.) [U. S. N. M.] One 9 . 



This species is quite difficult to distinguish in the female sex 

 from the allied S. desiUens Scudder, but the color of the caudal tibiae, 

 i.e., varying shades of glaucous in cequalis and reddish in desiUens, 

 appears to be a convenient character by which to separate specimens. 



