248 HYDROPHiLiD.E. [Ill/drama. 



II. Each elytron witb at most six rows of punctures between 

 the suture and the humeral angle. 

 i. Punctuation of elytra very strong and regular and 

 plain to apex. 



1. Length 2 mm.; elytra parallel-sided, rounded 



at apex only H. GEACILI3, Germ. 



2. Length l^ mm. ; elytra with sides rounded and 



dilated behind middle, sharply truncate at apex . H. ATRICAPIL'LA, Wat. 

 ii. Punctuation of elytra more or less coufused, espe- 

 cially towards apex. 



1. Thorax conUform, sides sinuate; elytra con- 

 fusedly punctured H. ptgm^a, Wat. 



2. Thorax hexagonal; elytra punctured in feeble 



rows on disc H. pulchella. Germ. 



H. testacea, Curt. Head black, strongly punctured, palpi testa- 

 ceous ; thorax about as long as broad, side's feebly angular in middle, 

 contracted towards base, testaceous with disc darker, stroligly and some- 

 what rugosely punctured ; elytra testaceous, widened behind, each with 

 eight rows of strong punctures between the sutiire and humeral angle ; 

 nnderside black ; metasternum with three raised lines, the middle one 

 bifurcate : this latter character serves to distinguish tliis species from all 

 the others. L. H-l| mm. 



Local ; found in both stagnant and running water; Lee, Battersea Fields, Epping, 

 "Woking, Cowley ; Holm Bush, Brighton ; New Forest ; VVicken Fen ; York ; Scot- 

 land, rare. Lowlands : in pools by the side of the Cairn at Irongray in the Solway 

 district. 



ZZ. palustris, Er. Considerably smaller than the preceding ; head 

 black, strongly punctured, palpi testaceous ; thorax black, quadrate, con- 

 tracted behind, strongly punctured,. with extreme margins usually plainly, 

 but sometimes obscurely, testaceous ; elytra considerably broader than 

 thorax, rather widened behind, with nine or ten rows of moderately 

 strong punctures between the suture and humeral angle ; legs testaceous. 

 L. 1^ mm. 



Stagnant ponds and ditches; rare, and very local; it may usually be found 

 sparingly at Abkham Bog, York, and it lias also been taken at Cowley (London 

 district), and in Bewdley Forest. 



H. riparia, Kug. Eather elongate ; head and thorax brownish- 

 black, the former rugosely punctured in front, the latter with the length 

 a little less than the breadth in middle of sides where they are slightly 

 angular, and thence contracted in almost a straight line to base ; punctua- 

 tion of thorax strong ; elytra brownish • black or blackish with sides 

 subparallel, not, or'very slightly dilated behind, with nine or ten rows 

 of almost square punctures on each between the suture and the humeral 

 angle ; legs and palpi reddish testaceous. L. '2^-2^ mm. 



Found in both stagnant and I'unning water ; common and widely distributed through- 

 out the country ; Scotland, common. Lowlands ; IreLmd, near Dublin and Waterford, 

 aud probably common. 



H. uigTita, Germ. (pusiJI a, Ste-ph..). Very like the preceding, with 



