of the Royal Physical Society. 331 



exterior margin slightly raised and reflexed posteriorly ; clypeus 

 slightly emarginate, with a deep square depression in the middle 

 of the anterior margin, and two large fovea? in each of the 

 anterior angles. Thorax convex, without marginal line, except 

 a very faint one on each side in front, with a linear depression 

 from each anterior angle reaching almost to the basal margin, 

 curved inwards, deepest in front, and leaving a broad marginal 

 space widest behind : the appearance of this line reminds one 

 of a bridle lying on the neck of a horse ; it is, however, very 

 faintly recurved near the base : dorsal line faint, reaching neither 

 to the anterior nor basal margins. Scutellum large. Elytra 

 punctate-striate ; interstices convex; the short scutellar stria 

 along with the sutural stria converging to meet the third and 

 fourth striae at the base; the second stria straight; the striae 

 deepest towards the apex, which is slightly sinuate. Under side 

 with theepisterna and sides of the metasternum punctate; sides of 

 abdomen slightly punctate ; the prosternum slightly prolonged 

 behind, with the prolongation margined, Tibiae short ; anterior 

 tibiae broad and triangular ; anterior tarsi piceous, in the male 

 with the first three joints very broad and transverse, and the 

 fourth very small. 



The most striking character in this species is the form of the 

 mandibles and the projecting prosternum; the former might 

 perhaps justify its establishment as a subgenus, and the latter 

 would seem to approach it to the genus Lonchosternus of Laferte, 

 of which the only character differentiating it from Codes is the 

 prosternum prolonged as in Hydrophilus. The projection here 

 has no pretensions to such an extensive prolongation, but it 

 may be viewed as the passage leading to it. The species is 

 readily recognized by these characters, and by the bridle-shaped 

 depression on the thorax. 



2. 0. politus, mihi. 



Niger, nitidus, impunctatus, politus ; antennis fuscis, ad basin 

 ferrugineis; mandibulis ferrugineis, acutis, supra haud con- 

 vexis ; capite et thorace lsevissimis, hoc stria marginali tenui 

 laterali et anteriori; elytris politis, leviter striato-punctatis, 

 interstitiis planis, spatio marginali opaco, ad apicem latiore. 



Long. 4 J lin , lat. 3 lin. 



Black, shining, impunctate, and polished. Head smooth, with 

 scarcely any depressions; antennae with the first three joints fer- 

 ruginous, rest dusky ; palpi piceous ; terminal joint of maxillary 

 palpi elongate and ovato-cylindric (rest wanting in my specimen) ; 

 mandibles ferruginous, darker at tip, small, not convex, triangular, 

 making the muzzle sharp, nearly straight on the outer side, 

 slightly curved and without teeth on the inner ; clypeus large, 



