LARVAL FORMS OF COLEOPTERA 



sis from European caves; urogomphi short, terete, and 

 curved toward each other in Evarihrus, in the other genera 

 long and multinodose) Pterostichinae (Genera as 



placed in Leng's Catalogue in 

 tribes Pterostichini and Platy- 

 nini) (pi. 4 F-H) 

 19. Each leg with two claws of equal length ; stipes stout and more 

 or less distinctly divided into a proxistipes and a dististipes 

 of about the same size ; lacinia with moderately strong, lateral 

 or terminal seta. (Anterior margin of nasale varying much 

 according to genus, in Zahrus produced into two conical 

 teeth ; retinaculum very small ; urogomphi solid, nodose, usu- 

 ally of moderate length, short in Zahrus and Percosia.) 



Amarinae {Zahrus and the gen- 

 era placed by Leng in Amar- 

 ini) 

 Each leg with two claws of different length; stipes normal, 

 rather slender ; lacinia with very strong, spinelike, terminal 

 seta. (Anterior margin of nasale varying much according to 

 genus, but never produced into a pair of strong, conical 

 teeth; retinaculum well-developed; inner edge of mandible 

 in front of retinaculum either entire, serrate, or with one to 

 several teeth; urogomphi usually of moderate length, short 

 in a few genera as C rat acanthus in which the pygopod is ex- 

 ceptionally short and thick ; trochanter with one or two rows 



of spines on each side) Harpalinae (genera as placed by 



Leng in his tribe TIarpalini) 



B.III. DYTISCIDAE 



Key to Subfamilies 



1. Head with anterior, distally notched prolongation; mandible 



turned upward with apex fitting into the notch of the prolon- 

 gation; maxillary palpus three- jointed 



Hydroporinae {H y p h y d r u s, 

 etc.) (pi. 6 B-D, G) 

 Head without anterior prolongation; mandibles directed for- 

 ward ; maxillary palpus four-jointed or more 2 



2. Maxillary stipes Ijroad, suboval, with one or two strong hooks 



on inner margin 3 



Maxillary stipes slender and long, no hooks on inner margin 5 



3. Seventh and eighth abdominal segments laterally without series 



of swimming hairs ; ligula absent . 



Colymhetinae {Agahus, Ilyhius, 

 Colymhetes, Rhantus, and 

 also Laccophilus) 

 23 



