9 (4) Abdomen with pleurites on at least the first 6 segments; 

 ventral surface of thorax sclerotized, usually with 

 sternites; thoracic pleurites often divided into 2 

 or 3 parts; apex of ninth abdominal segment typically 



emarginate ELMIDAE 10 



Abdomen with pleurites present on only first 4 segments; 

 with erect hairs along medial margin of each narrow, 

 undivided thoracic pleurite; thoracic sternites 

 membranous or absent; apex of ninth abdominal segment 

 evenly rounded; each eyespot with 5 ocelli and with 

 another ventral ocellus below base of antenna; body 

 robust; head almost as wide as thorax, but usually re- 

 tracted within it (Figs 136, 137, 138): 



LIMNICHIDAE: Lutrochus 



(Larvae of the other genera are unknown; they are probably 

 not aquatic.) 



136 



Figs 136-138 Larva of Lutroohus luteus: 136- dorsal 

 aspect; 137- ventral aspect; 138- lateral aspect. 



10 (9) Abdomen with pleura on first 8 segments 11 



Abdomen with pleura on first 6 or 7 segments. , .ELMINI 16 



11 (10) Body rather broad, lateral margins expanded. .. .LARIN I 12 



Body slender, elongate, cylindrical or hemicylindrical 



ELMINI, in part 13 



12 (11) With coarse, prominent spines along lateral margins; 



dorsal surface ridged on each side; last segment rather 

 square-sided and flat dorsally; procoxal cavities 

 open behind; up to 16 mm long (Figs 139, 140): Lara 

 Without marginal spines; body quite flattened and with 

 rather smooth surface; testaceous to brown, somewhat 

 translucent; procoxal cavities closed behind (Figs 

 141, 142): Phanoaerus 



57 



