IIYDIJOrHILIDES. 120 



Antennae ci!::!:lit-jointed ; elytra truncate at apex ; pos- 

 terior til)iae and tarsi not at all or very slightly fringed. 

 Body oval. Limnchiiis, Leach. 



C Alxlonien with four visil)le ventral segments, the first 

 two segments being covered by two plates, meeting in 

 tlie ndddle. 



Antennae nine-jointed ; til)iae with fine spines, tarsi 

 somewhat compressed. Chaetarthria,Viat. 



Hydrophilus, 



Oblong oval, moderately convex. Pitch-black ; antennae 

 rust-red, club l3rown. Elytra with a tooth at apex ; abdo- 

 minal segments ridged. L. 17 — 20 1. Common. 



H. 2nccu8, Lin. 



Hydrous. 



Oblong oval. C4reenish-black ; antennae rust-red, cluli 

 brown ; legs brown-l)lack. Elytra with some rows of 

 punctures. L. 7 — 8 1. Kather common. 



H. carahoides, Lin. 



Hydrohius. 



A, Elytra with punctured striae, interstices closely punc- 

 tured, alternate interstices with a row of larger punc- 

 tures. 



Pitch-black; antennae (except club) and legs brown. 

 Posterior femora pubescent for at least | of their length. 

 L. 3J 1. Common. H.fuscipcs, Lin. 



J?. Elytra with rows of fine punctures, interstices closely 

 punctured, alternate interstices with a row of larger 

 punctures. 



Black ; antennae (except club) and tarsi reddish. Pos- 

 terior femora pubescent at base only. Body more elongate 

 than H. fuscijws. L. -1 1. Not uncommon. 



H. olloiKjus, Herbst. 



Ilelochares. 



A. Punctuation scarcely strong, finer and more scanty 

 toward apex of elytra. 



