HYDRO PHILIDiE. — HYDROBIUS. 12'T 



Genus CIV. — Hydrobius, Leach. 



Maxillary palpi considerably longer than the labial, the basal joint minute, the 

 second elongate-clavate, third and fourth of nearly equal length, the latter 

 elongate-ovate, obtuse: lahrum transverse, entire. Antennas nine-jointed; the 

 basal joint robust, elongate, clavate, the second shorter and more slender, 

 attenuated at the apex ; the following nearly of equal length, clavate ; the two 

 next short, transverse; the remainder forming the club, the terminal joint 

 being acuminated : head ovate : eyes small, not prominent : clypeus entire : 

 body more or less convex : elytra entire, obtuse : sternum simple : tibia? slightly 

 spinose : posterior tarsi natatorious, ciliated : claws simple. 



Hydrobius, the last of the aquatic genera, differs from the 

 other Hydrophilidse by the greater convexity of the body, which is 

 posteriorly obtuse : the clypeus is entire, the scutellum small, the 

 sternum simple, the antennae nine-jointed, with the terminal joint 

 large, somewhat compressed and acuminated. In the first subdi- 

 vision of the second section of the genus, the maxillary palpi are 

 very long, and the terminal joint is considerably shorter than the 

 third ; and in the succeeding subdivision they are abbreviated, and 

 have the terminal joint longer than the third : they may probably 

 form different genera hereafter. 



A. Body more or less elongate, a. Elytra striated throughout. 



Sp. 1. picipes. Oblongus, nigro-piceus, nitidus, punctatus, pedibus dilutioribus, 

 tibiis tarsisque rufescentibus, elytris obsolete striatis. (Long. corp. 3g — 4. lin.) 

 Hy. picipes. Fabricius. — Steph. Catal. p. 60. A T o. 603. 



Oblong, deep pitchy-black, or obscurely ameous, shining: thickly and finely 

 punctate : head with a few larger punctures on the sides and near the eyes : 

 thorax also with some larger impressions on the lateral margins ; and two slight 

 fovea? on the disc towards the anterior edge : elytra obsoletely striated, the 

 strise composed of remote impressions, the alternate interstices with an irregular 

 line of larger punctures : body dull black beneath : legs piceous, with the 

 tibia? and tarsi rufescent or rufo-ferruginous. 



Var. j8. Rather broader ; more coarsely and thickly punctate, with the striae on 

 the elytra more distinct; the palpi pale testaceous, with the apex black, and 

 the legs pale rufo-testaceous with the femora dusky. Probably a distinct 

 species. 



Not very common near London, but more abundant in the marshes 

 towards the mouth of the Thames. " Lake of Killarney. , ' — 

 Dr. Leach. " Southend."— Rev. F. W. Hope. " Wln't^esea-mere." 

 Messrs. Chant and Beniley. " Brackish waters near Gravesend, 

 not uncommon." — Messrs. Stone and Bainbridge. 



