JAMES A. G. REHN 
179 
him, blit unfortunately he descrilied the wrong one. Scudder’s 
interpretation of thalassinus is incorrect, a Nevada specimen so 
labelled and referred to by him now lieing liefore us. The green- 
ish blue tinge of the wings in this and certain other individuals 
jirobably misled him. True thalassinus is a very different species 
of which we have studied consideralile series. 
The Rahula Group of the Genus Circotettix 
This group is made up of a single widely distributed species, 
ranging from ('anada to southern New Mexico in the C’ordilleran 
and adjacent I'egions, and divisable into three geograjihic races, 
one of which is new. 
Circotettix rabula Eehn and Ilebard {Circotettix undulatus of 
most authors, not of Thomas.; 
190(). Circotettix rahula Rehn and Hebard, Proc. Acad. Nat. Hci. Phila., 
190G, p. 393, figs. 13 and 14. i cf 9 ; iMammotli Hot Springs, Yellowstone 
National Park, Wyoming.] 
The three geographic races of this species are as follows: 
Circotettix rahula rahula. A northern form occurring in the 
United States in the Transition and upper portion of the Upper 
Sonoran Zones from Afontana to Colorado, in Canada ranging 
into the Boreal Zone. 
Circotettix rahula uigrajasciatus. A form occurring over a 
considerable portion of the UiRier Sonoran Creat Plains in South 
Dakota, Nebraska, Colorado anil Kansas. 
Circotettix rahula altior new sulispecies. A form of the Boreal 
Zone within the United States, typical from northern CVilorado 
to southern New Alexico. 
Intergradation lietween these races is established by the ex- 
tensive material liefore us, summarized discussion of which is 
given below. 
Circotettix rabula rabula Rehn and Ilebard (Plate XI, fig.s. 7 to 9.) 
This the typical race is characterized within the siiecific as- 
semblage by having a generally weaker and more broken wing- 
band than in C. rahula nigrafasciatus, shorter and broadei’ wing 
than in same, with an average lilunter api'x; broader tegminal 
apex and more heavily incrassate radiate vi'ins of thi' wing. 
From C. rahula altior the present race dilfi'rs in the proport ionati'- 
TRAXS. AM. EXT. SOC., .XI.VII. 
