34 (33) Apex of ninth abdominal segment narrowly emarginate 



(i.e., with a distinct notch) (Figs 189, 190): Acneus 

 Apex of ninth segment truncate or broadly arcuate 35 



35 (34) Ninth abdominal segment not rectangular, the sides 



expanding from base toward broadly arcuate apex; 

 lateral expansions of eighth segment short, not 

 forming part of lateral margin of body outline 

 (Figs 191, 192): Dicrcmopselaphus 



Ninth abdominal segment almost rectangular; lateral 

 expansions of eighth segment forming part of margin 

 of body outline (Figs 193, 194) : Eatopria 



36 (33) Eighth abdominal segment with lateral expansions; 



abdomen with 4 pairs of gills (Figs 195, 196): Eubrianax 

 Eighth abdominal segment without lateral expansions; 



abdomen with 5 pairs of gills (Figs 197, 198): Psephenus 



67 



