110 MANDIBULATA. — COLEOPTERA. 



Genus XCV. — Hydrochus, Germar. 



Palpi with the last joint oval, stout : maxillary much shorter than the antenna? : 

 clypeus entire : mandibles rather stout, trigonate, ohsoletely emarginate at the 

 apex, acute : mentum rather large, subquadrate. Antenna* with the four ter- 

 minal joints produced into a slightly compressed elongate club : head porrect : 

 eyes very prominent : thorax elongate-quadrate : body nearly linear. 



The prominent eyes and elongate body well distinguish this genus 

 from Helophorus, and its stout, ovate, terminal joint of the palpi at 

 once discriminate it from Ochthebius and Hydrsena. 



Sp. 1. elongatus. Nigro-piceus, aut ameo-nigricans, elytris prqfunde punctato- 



striatis, interstitiis alternis carinato-elevatis. (Long. corp. if — 2 lin.) 

 El. elongatus. Fabricius. — Hy. elongatus. Steph. Catal. p. 56. No. 565. 



Pitchy-black, sometimes slightly glossed with brassy: head porrect, rugose- 

 punctate: thorax deeply punctated, with five impressed dots, three placed 

 transversely and two oblong, towards the scutellum : elytra convex, dilated on 

 the sides, deeply punctate striated, the interstices narrow, the second from the 

 suture anteriorly, the third posteriorly, and the fourth, sixth, and eighth en- 

 tirely, somewhat elevated : body pitchy-brown beneath : the abdomen rugose, 

 foveolated : legs and antennae pitchy. 



Taken occasionally in April and May on the banks of ponds in 

 Battersea-fields and on Wandsworth-common. " Spitchweek." — . 

 Dr. Leach. " Netley, Salop, common." — Rev. F. W. Hope. 



Sp. 2. crenatus. JEneo-aut viridi-niger, elytris crenato-st?natis, pedibus rvfo- 



piceis. (Long. corp. 1 J — if lin.) 

 El. crenatus. Fabricius. — Hy. crenatus. Steph. Catal. p. 56. JVo. 566. 



Brassy or greenish-black, shining : head porrect, thickly punctulated, with several 

 elevated longitudinal lines on the vertex : thorax thickly punctured, with three 

 transverse impressions anteriorly, and one on each side posteriorly near the 

 hinder angle : elytra slightly dilated on the sides, deeply crenate-striated, the 

 intermediate interstices scarcely elevated : body beneath punctulated : legs 

 and antennae pitchy-red or testaceous, the latter with the tip of the club black. 



Not uncommon on the muddy banks of ponds on Wandsworth- 

 common, and on the borders of ditches on Ockham- heath, near 

 Ripley, in April and May : also found near Hertford, and on the 

 banks of the Orwell. " Netley, common." — Rev. F. W. Hope, 



Sp. 3. brevis. Brevior, niger, thorace foveolato, antice latiorip elytris punctato- 



striatis, interstitiis alternis elevatis. (Long. corp. 1^ — 1£ lin.) 

 El. brevis. Herbst. — Hy. brevis. Steph. Catal. p. 56. 2Vo. 567. 

 Short, subovate, deep shining black : head broad, trunctate : thorax broader an- 



