122 MANDIBULATA. COLEOPTERA. 



Sp. 9. nitidus. Ovatus, depressus, ater nitidus, margine thoracis pedibusque pal- 



lide rujis. (Long. corp. \ — f lin.) 

 Hy. nitidus. Marsham. — Li. nitidus. Steph. Catal p. 59. No. 596. 



Ovate, depressed, glossy-black, with the margin of the thorax and the legs pale 



rufous, or piceous. 

 Distinguished by its depressed form and minute bulk from all the foregoing. 



Of Li. nitidus I have also only seen my own pair, which were ob- 

 tained from the same source as the preceding. 



Genus C. — Hydrous, Linne MSS. 



Maxillary palpi very long, the basal joint minute, the second very long, robust, 

 subclavate, the third shorter and more slender, the terminal about half the 

 length of the third, slenderer and elongate-ovate : labrum transverse-oval, 

 entire: mandibles large, emarginate at the apex, with several strong bifid 

 teeth in their inner edges: Antenna? nine-jointed*, the basal joint robust, bent, 

 attenuated at the base, the next oblong, the three following transverse, the 

 remainder forming the club, of which the terminal joint is acuminated; 

 head broad, obtuse : eyes not very large : elytra posteriorly attenuated : ster- 

 num terminating in an acute spine, reaching considerably beyond the in- 

 sertion of the posterior legs ; four posterior tarsi compressed, ciliated on the 

 inner margin, and formed for swimming ; claws bifid ; and two anterior tarsi 

 of the male with a triangular dilatation, and two robust simple unequal claws. 



Hydrous is readily known by the integrity of the labrum, bifid 

 posterior claws, attenuated elytra, and superior bulk ; as well as 

 from the magnitude and internal denticulation of its mandibles ; and, 

 like the Dytici, the males are remarkable for the great size of the 

 terminal joint of the anterior tarsi. 



Sp. 1, piceus. Olivaceo-niger, nitidus, elytris octo striatis, inter stitiis inter- 

 mediis lined punctorum impressorum, antennis rufescentibus. (Long. corp. 1 

 unc. 4 — 6 lin.) 



Hy. piceus. Linne. — Hy. piceus. Steph. Catal. p. 59. No. 597. — Curtis, v. 

 pi. 239. 



With the exception of Lucanus Cervus and Melolontha Fullo, this is the largest 

 of the indigenous Coleoptera: of a glossy olivaceous-black, the margins of 

 the elytra purpurascent or greenish : head smooth, with a deep punctate im- 

 pression above the eyes and on the forehead; thorax smooth, with some 

 punctures on the lateral margins, and two more or less evident punctate fovese 



* " Olivier remarks that the antennae of Hydrous piceus are in fact eleven- 

 jointed, the eighth and tenth joints being very minute, their place being marked 

 out by the distances which intervene between what are commonly considered 

 the second and third, and the third and last joints of the clava." — Mac Leay. 



