ACRIDIIDAE TRYXALINAE 2 5 



TRYXALINAE. 



This subfamily has a varied development in the United States, 

 where at least thirty-five genera occur, none of them very rich in 

 species, though most of the genera are endemic. 



The following table to separate them is copied from McNeill's 

 just published Revision of our Tryxalinae, excepting as it is 

 altered to correct some slight clerical errors, to change some 

 generic names, to include the genera purposely omitted by him, 

 which seem to me (contrary to an opinion formerly expressed 

 Psyche, v, 431 seq.) to belong here, and to omit one genus 

 belonging elsewhere. The order and alliance of genera in this 

 table (especially as here altered) leave much to be desired, but 

 the construction of a substitute would too long delay the publica- 

 tion of this Guide, which has been awaiting the appearance of 

 Professor McNeill's paper for its completion. 



Genera of Tryxalinae. 



a l . Head distinctly longer than the pronotum ; eyes very oblique, 

 nearly horizontal ; metasternal lobes contiguous. 



ft 1 . Tegmina very much shorter than the abdomen; spines of 

 posterior tibiae minute and numerous, about twenty-five. 



Rhadinotatum McNeill. 



b 2 . Tegmina exceeding the abdomen ; spines of posterior 

 tibiae less numerous, about sixteen. Achurum Saussure. 



a 2 . Head sometimes equalling, never exceeding, the pronotum 

 in length. 



b !. Head ascending, more or less conical, the occiput elevated 

 considerably above, or inclined upward at a distinct angle with, 

 the pronotum. 



c 1 . Head as viewed laterally strongly ascending or greatly 

 raised above the pronotum. 



d l . Upper half of head markedly conical; face below 

 fronto-vertical process subperpendicular ; antennae more 

 than half as long as tegmina. 



e l . Metazona much longer than prozona, with an ele- 

 vated crest. . . . Acrolophitus Thomas. 





