46 MANDIBULATA. — COLEOPTERA. 



Genus LXXX. — Hygrotus,* mihi. 



Palpi, external maxillary with the terminal joint stout, tumid, ovate conic^- 

 acute: labrum minute: mandibles deeply notched at the apex: mentum tri- 

 dentate anteriorly. Antenna short, the two basal joints rather elongate; the 

 third and fourth very stout, equal in length; the remainder rather stouter 

 and longer, the terminal being longest : head broad, depressed : scutellum none : 

 body sub-globose, very convex, as high as broad : elytra ovate : legs elongate ; 

 the four anterior tarsi with four, the two posterior with five joints; all 

 didactyle. 



Hygrotus differs from Hydroporus by the superior convexity of 

 the body, the more deeply einarginated apex of the mandibles, the 

 swollen and acute terminal joint of the external maxillary palpi, 

 and by the brevity of the third and fourth joints of the antennae : 

 the genus very much resembles the preceding one, but from that it 

 is readily known by the didactyle posterior tarsi. 



Sp. 1. fluviatilis. Plate XI. f. 2. Flavo-testaceus, thorace utrinque striold 

 acuid impressd, elytrorum disco nigro, Jlavo-maculato. (Long. corp. 1^ — 

 If lin.) 



Hyd. fluviatilis. Leach MSS. Hyg. fluviatilis. — Steph. Catal.p. 44. No. 429. 



Testaceous-yellow above, very obscurely punctulated : head pale, eyes dusky : 

 thorax with a transverse elevated disc, and on each side a curved impressed 

 line, the base obscurely impressed ; on the disc is an abbreviated transverse 

 spot, which becomes attenuated on each side : elytra very finely punctulated, 

 obsoletely striated, with two of the striae more distinct and punctated ; the 

 disc with a large, irregular, black patch anteriorly, united by a smaller pos- 

 terior one and by three or four black lines, leaving an irregular patch towards 

 the suture, and a rounded one on the lateral margins, as well as the apex, 

 base, and margins, of each elytra, yellowish : body beneath testaceous, finely 

 punctulated : legs testaceous. 



Not found in the vicinity of the metropolis, but a native of hilly 

 and mountainous districts. " In the river Cawdor, near Carlisle, 

 and in the Tavy, in Devonshire." — Dr. Leach. " Netley, Salop, 

 very abundant." — -Rev. F. W. Hope. 



Sp. 2. assimilis. Supra ferrugineus, thorace utrinque impresso, elytris lineis 



nigris ahbreviatis. (Long. corp. 1^ lin.) 

 Dy. assimilis. Paykul. — Hyg. assimilis. Steph. Catal. p. 44. No. 430. 



Above ferruginous and thickly punctulated : head with a narrow fuscous mar- 

 gin to the vertex : thorax with the sides rounded, transversely convex in the 



* ty^orm, humiditas. 



