96 INSECTA MADERENSIA. 



Head and prothorax densely and minutely punctulated ; the latter with the sides hroadly testaceous. 

 Ell/Ira closely substriate-punctate (the punctures having generally only a tendency to arrange 

 themselves in longitudinal rows) ; pale testaceous, and more or less densely mottled, or be- 

 sprinkled (especially on the disk), with black. Lec/s, palpi and antenna either testaceous or else 

 very pale ferruginous. 



The Madeiran specimens of this common Evu-opean insect differ in being a little 

 larger and less shining than the ordinary type, and in having the pimctui-es of 

 their elytra somewhat less distinct and not quite so regularly disposed in striae. 

 It is decidedly rare, being confined almost exclusively, like the lAmnebius gran- 

 (JicoUis, to lofty positions Avithin the sylvan districts. I have taken it at the 

 Ribeiro Frio, in the spring; in the small trickling streams of the Cruzinhas, 

 adhering to submerged leaves ; and in similar spots at the head of the Eibeii'o 

 Fundo, on the northern edges of the Fanal, — during July. 



Gemis 34. HYDROBIUS. 



Leach, Zool MisceU. iii. 93 (1S17). 



Corpus vel mediocre, vel (ut in specie Maderensi) parvum, oblongo- vel rotundato-ovale : prothorace 

 postice lato : mesnsterno carinato : alls (in typicis amplis, scd in specie nostra) obsolctis. An- 

 tennce 9-articulat:c breves, articulo primo elougato crasso flexuoso, secundo paulo breviore sub- 

 cylindrico, tertio brevi, quarto quintoquc brevissimis, sexto lato subpoculiformi, reliquis validiori- 

 bus, clavam magnam oblongam pubescentem triarticulatam efficientibus, ultimo (in typicis vel 

 acuminato vel oblongo, sed in nostra) globoso. Labrum transversum, antice leviter emarginatum. 

 MandibuliB breves latie obtectfc, apice incurvre acutie fissa;. Maxilla bOobpe : lobo externa brcvi 

 lato, apice dense barbato : internu paulo breviore angustiore, intus ad apicem barbato eihato, mar- 

 gine intemo membrana instructo. Palpi inaxiUares breviusculi robusti, articulo ultimo penultimo 

 lougiore ; labiates mcdiocres. Mentum amplum, transverso-quadratum, margine antico rotundato 

 sed ad summum apicem ssepius le\iter emarginato. Ligula lata, apice fissa, aut potius biloba, 

 lobis rotundatis ciliatis. Pedes subnatatorii, robusti, antici vis breviores : femoribus tibiisqae 

 subcompressis : his roctis spinosis, valde calcaratis, apicem versus (prjesertim anticis) leviter 

 dilatatis : tarsis {prxcipue pusteriuribus) parce ciliatis, articulo primo brevissimo, secundo arete 

 connato. 



In addition to minor points of distinction, sufficiently apparent, Hi/drobius may 

 be known from Laccohins ])y its 9-jointed antenna?, by tlie absence of any indica- 

 tion of a cui'ved hook to the outer lobe of its maxillye, and by its miiformly 

 straightened tibise. The minute and suborbicular form of a few of the species 

 which compose it (represented in Madeira by the only member of the group 

 which I have hitherto been able to detect) gives them, at fii'st sight, a strong 

 resemblance to Ch(etorthria, Waterh. (Stcph. ///. Brit. Ent. a.d. 1832 •,= CiiUidh(m, 

 Erich. Kdf. der Jlar/c Brand, a.d. 1837) ; but the simple sternum of that genus, 

 added to the slender and very elongated basal, and the short, thick, and globose 

 second, joints of its antennaj, and the large penultmiate (and small, truncated 



