104 NORTH AMERICAN ACRIDIDAE (oRTHOPTERA) 



the more so. Male supra-anal plate shield-shaped. 'Male sub- 

 genital plate elongate conical, its ventral length less than that 

 of the preceding sternite. 



Truxalis brevicornis (Johannson) (Plate IV, figure 10.) 

 1764. [Gryllus] brevicornis Johansson, Amoenit. Acad., vi, p. 398. [Xorth 



America.] 

 1773. Acrydium ensicornu DeGeer, Mem. I'Hist. Ins., in, p. 499, pi. 42, 



fig. 7. [Pennsylvania.] 

 1861. Ox[ycoryphus] burkhartianus Saussure, Rev. et Mag. de Zool., xiii, 



p. 314. [cf, Mexico.] 

 1894. Truxalis brevicornis BeutenmiiUer, Bull. Amer. Mus. Xat. Hist., vi, 



p. 291, pi. VIII, figs. 1 and 2. [New York, New York.] 

 1896. Tryxalis brevicornis Morse, Psyche, vii, p. 383, pi. 7, figs. A, Aa and 



Ab. 

 1916. Truxalis breincornis Rehn and Hebard, Proc. Acad. Nat. Sci. Phila., 



1916, p. 155. (Discussion and many records from the southeastern United 



States.) 



Though frequentlj^ appearing in the literature, the other 

 records of this species add little but distributional data to those 

 given a])ove. 



An average increase in size southward occurs in the species. 

 Individuals from different localities in the same region, how- 

 ever, sometimes show very marked size difference. This is 

 particularly demonstrated by males before us from Houston 

 and Harrisburg, Texas. 



Comparison of North American individuals with material 

 from Mexico, Costa Rica, British Guiana, Brazil, Paraguay and 

 Argentina shows no tendency whatever toward racial differen- 

 tiation. 



Measurements {in millimeters) of average specimens and extremes 



