30 OETHOPTEKA. 



the head and pronotum together; fastigium of the 



vertex without a median carina; scapular area of 



the tegmina not specially dilated. 



/. Tegmina obliquely truncate at apex. 



g. Sides of the vertex more or less evenly rounded, 



so as to render the fastigium blunt rather than 



angulate ; lateral foveolae very obscure ; antennae 



basally much depressed in both sexes, ensiform ; 



lateral carinas of pronotum straight or but gently 



diverging posteriorly [Orphula, Stal *.] 



gg. Sides of vertex straight, rendering the fastigium 

 angulate ; lateral foveolae more or less evident, 

 linear to sublinear ; antennas basally less de- 

 pressed, scarcely ensiform even in the female; 

 lateral carinas of pronotum considerably diverging 



posteriorly Thyriptilon, Bruner. 



ff. Tegmina more or less evenly rounded at apex. 



g. Lateral carinas of pronotum less prominent than 

 the median, more or less divergent, especially on 

 metazona; prozona and metazona about equal 

 in length ; the lateral lobes deeper than long. 

 h. Lateral carinas nearly or quite as well developed 

 on the prozona as on the metazona ; eyes more 

 or less truncate anteriorly. 

 i. Antennas longer, somewhat exceeding the com- 

 bined length of head and pronotum, filiform ; 

 the apical half or two-thirds (?) of tegmina 

 membranous; wings usually more or less 

 coloured and decidedly infuscated. 

 j. Tegmina rather broad; wings more or less 

 evenly tinged with yellow or orange on basal 

 portion, apically infuscated. Pro- and meta- 

 zona of pronotum of equal length ? . . . Sisantum, Bruner. 

 jj. Tegmina narrow ; wings fuscous, the anterior 

 margin apically black-bordered. Pronotum 

 with the prozona a little longer than the 



metazona Orphulina, Giglio-Tos. 



ii. Antennas shorter, but little or not at all exceed- 

 ing the combined length of the head and 

 pronotum ; the apical third only of tegmina 

 membranous ; wings clear or but little infus- 

 cated. 



* This genus does not appear to be represented in that portion of America covered by this work, but is 

 introduced here to Bhow its relationships. I cannot agree with Scudder and others as to the position occupied 

 by it (see my paper on " Locusts of Argentina " ; also anted, p. 26). 



