Mr. G. R. Waterhouse on some Heteromerom Coleoptera. 317 XXXV. — Descriptions of some new genera and species of Hetero-merous Coleoptera, By G. R. Waterhouse, Esq. Platesthes, nov. gen. Head rather short, the lateral lobes or ridges protecting the base of the antennse, less prominent than the eye. Clijpeus separated from the head by a distinct transverse impres-sion, and by two less distinct lateral grooves ; the anterior mar-gin slightly emarginated. Eyes transverse, convex, rather large and distinctly emarginated in front. Labrum prominent, transverse, distinctly emarginated in front. Mandibles moderate, bidentate at the apex. Maxilla with the outer lobe entirely uncovered by the mentum : the maxillary palpi moderate, the terminal joint triangular. Labial palpi short and stout, the terminal joint truncated. Mentum broader than long, foui'-sided, the hinder margin di-stinctly shorter than the front, wdiich is obscurely emarginated, but nearly straight. Labium transverse, corneous, exposed. Throat-plate^ with a narro\Aash oblong polished and transversely grooved area in the middle, joining the mentum by a straight margin. Antennce rather long and slender ; if extended backwards would nearly reach the base of the thorax ; the joints, most of them, of a long obconic form ; the second joint short, the third scarcely longer than the fourth ; the three terminal joints distinctly broader than the rest, the last of a short ovate form and equal to the penultimate. Thorax large, very nearly equal in width to the elytra, and nearly quadrate, but slightly narrower in front, the outer edge emar-ginated, the posterior margin very nearly straight, and not closely applied to the elytra ; the angles nearly right angles, but slightly rounded ; the upper surface slightly convex in the middle, but the lateral margins are recurved ; the w hole dorsal surface however is pretty nearly flat. Scutellwn very broad, but rather short, and obtusely pointed be-hind. Elytra soldered together at the suture ; oblong ; the dorsal sur-face nearly flat, the sides parallel, but on the posterior third gradually contracted, so that the outline of that region would form half an oval ; the apex however is produced, recurved and * This part, which I terra throat-plate^ often furnishes somewhat import-ant characters : it is the mesial part of the head beneath, below (or behind) the mentum.
BioStor
