472 llev. H. Clark on some Sjjecies 



basin et oculorum margines late nigro-fusco sparsim punctulato, inter 

 et infra oculos leviter bidepresso : thorace lato, bre'vi, lateribus obliquis 

 et subrotundatis, uiargine posteriors siuuato, non oblique curvato ; facie 

 sparsim pubescente et valde punctata (disco ad mediimi impunctato) ; 

 lateribus, angulis posticis, et margine ad basin subdepressis : elj-iris 

 subparallelis (pone medium sublatioribus), ad apicem sat productis, 

 pubescentibus, crebre punctatis, atris: antennis fuscis, articulis 1-4 

 flavis : pedibus rufo-flavis, tarsis anticis in c? latis, tarsis tibiisque pos- 

 ticis fuscatis. 

 Long. Corp. 2 lin., lat. 1 lin. 



Nearly allied to H. i^lanus, Fab., but slightly narrower, more 

 parallel, and not so rounded in form : in H. jilcmus the greatest 

 breadth is medial, in H. derdictus it is post-medial. The thorax of 

 H. planus is covered with minute punctures ; in the species before us 

 it is at the margins more coarsely punctured, and medially impunc- 

 tate : the basal outline is (by reason of the more distinct definition 

 of the medial scutellary angle) somewhat more sinuate ; the colour 

 of the head is entirely diiferent : the elytra are pubescent (not 

 simply glabrous), of a deep black colour (not fuscous or rufous black), 

 and more obviously punctate ; in one of the examples before me, 

 a $ , the colour is entirely opake, not shining, and the punctation 

 of the elytra appears to be somewhat closer : the tarsi are aU (in 

 every example) distinctly fuscous, and the anterior tarsi of the S 

 appear to be broader and more dilated. 



In colour of head and elytra, and in its fuscous tarsi, it more 

 nearly resembles H. enjtlirocepliahis, Linn. ; but this latter species is 

 very distinctly more rounded, and a smaller insect. 



I received six examples from a bird-collector in the island of 

 Orkney, whom I employed to collect water-beetles for me, in August 

 1855. The species probably was then abundant. During an entomo- 

 logical tour through the Western Isles of Scotland, last autumn, with 

 Mr. John Gray, in which we specially sought to collect Hydracle- 

 phaga, we were unable to meet with a single example of this species. 

 By the kind aid of M. Javet, M. Aube of Paris has been good enough 

 to examine a specimen which was retui'ncd by him " unknown." I 

 have a note that the species appeared to me to be very closely related 

 to H. lapponum, Gyll., of the collection of the Jardin des Plantes ; 

 but the opportunities that I have had of examining insects in that 

 museum have not been always very favourable ; and U. lapponum 

 of Gyllenhall is, according to examples I have received from M. 

 Boheman, narrower, less pubescent, more rufo-fuscous in colour, and 

 with the elytra more sparingly punctate. M. Thomson has described 

 a species (H. Bohemanni) which probably is very near to this species. 



