ACRIDIIDAE TRYXALINAE 29 



/i 1 . Hind tibiae never red. . Orphula Stal. 

 h 2 . Hind tibiae red. 



1 1 . Antennae depressed basally, long and 

 acuminate ; face strongly oblique. 



Alpha Brunner. 



1 2 . Antennae filiform ; face moderately oblique 

 in the male, subperpendicular in the female. 



Phlibostroma Scudder. 



e 2 . Tempora plain or foveolate, visible from above (in 

 Mecostethus small or minute, triangular and basal ; in 

 this case the intercalary vein is very strong) . 

 f 1 . The vertex is not bounded in front by a raised 

 line and, viewed from the side, does not form an 

 angle with the face; the tempora are very faintly 

 impressed spaces, which are strongly declivent ; inter- 

 calary vein of tegmina wanting. 

 g 1 . Tegmina plain ; lateral carinae of the pronotum 

 very little sinuate. . . Boopedon Thomas. 

 g 2 . Tegmina distinctly spotted ; lateral carinae of 

 the pronotum strongly sinuate. 



Plectrotettix McNeill. 



y 2 . Vertex bounded in front by a raised line; viewed 

 from the side it forms a more or less distinct angle 

 with the face, or it is not at ah 1 angulate. 



g 1 . Median carina of the pronotum high and sharp, 

 cut by the principal sulcus in or plainly in front of, 

 the middle ; intercalary vein very strong ; apical 

 spurs on inner side of posterior tibiae subequal. 



Mecostethus Fieber. 



g". Median carina of the pronotum rarely cut 

 plainly in front of the middle, and in this case it is 

 not high and sharp, or the intercalary vein is not 

 strong. (In Stirapleura and Psoloessa the inter- 

 calary vein is present but not very strong and the 

 inner apical spurs of the posterior tibiae are very 

 unequal). 



