TRICHOPTERYGIDAE. 359 



neath ; metasterniim produced tolerably far between coxae, 

 apex nearly straight, with acute angles ; posterior coxae 

 rather far apart, much dilated ; maxillary palpi with last 

 joint divided into two portions, apical ])ortion thin, slightly 

 cur\'ed, basal portion dilated, third joint much thickened, 

 longer than broad, considerably narrower at apex than in 

 middle, nearly ovate, second joint thickened at apex ; thorax 

 broadest at base, gradually narrowed in a curve toward 

 apex. Trichoiiteryx, Kirby, 



II, Thorax narrowed behind. 



1, Sides of thorax sinuate toward base. 



Mesosternum ridged; metasternum produced between 

 coxae, apex straight, with angles acute ; posterior coxae 

 somewhat far apart, much dilated; maxillary palpi with 

 last joint strongly curved, third joint much thickened, 

 longer than broad, nearly as broad at apex as in middle, 

 second joint somewhat thickened at apex ; thorax broadest 

 before middle. Micrus, Mat. 



2, Sides of thorax not sinuate toward base. 



A A. Thorax broadest before middle ; elytra 

 half as long again as head and thorax. 



Mesosternum not ridged, epimera inliexed far beneath ; 

 metasternum long, produced between coxae, apex strfiight ; 

 posterior coxae placed somewhat apart, simple ; maxillary 

 palpi with last joint bisinuate, third joint much thickened, 

 not much longer than broad, rather narrower at apex than 

 in middle ; second joint somewhat thickened at apex. 



Mi c r oj) tiliu m, Mat. 

 jB 2?. Thorax broadest behind middle ; elytra as 

 long as head and thorax. 



Mesosternum not ridged; metasternum not produced 

 between coxae ; posterior coxae placed apart, laminate ; 

 maxillary palpi with last joint moderately curved, third 

 joint thickened, longer than broad, narrower at apex than 

 in middle, nearly ovate, second joint much thickened at 

 •apex. Nephanes, Th. 



H, Elytra not, or only slightly abbreviated. 



a. Thorax broadest before base. 



I, Pygidium exposed. 



