86 INSECTA MADERENSIA. 



cliflFs over the road to Seisal, — wliere however it is more than probable that it had 

 been -washed do^ii from the lofty ravines above. On the upland plain of the Paul 

 da Serra, 5000 feet above the sea, I have captured it in profusion, from under 

 stones in the shallow pools and springs which feed the waters of the valley beneath ; 

 as also in similar positions at the Cruzinhas, in the Eibeu'O de Seisal, and at the 

 respective heads of the Ribeu'O Fundo and the Ribeiro de Joao Delgada : and Uke- 

 vnse, very plentifully at times, in. the levada of the Eibeu'o Frio, amongst moist 

 leaves and rubbish in spots from whence the water had retu'ed. 



Genus 27. HYDROPORUS. 



Clairv-iUe, Mit. Heh. ii. 1S3 (180G). 



Corpus ])arvum, oblongiim vel ovatum : prothorace basi in mcflio proclucto : alls amplis. Anfenrus 

 filiforraes. Labrum brevissimuiu ti'ansvcrsum, autice profunde euiarginatum. Mandibula breves, 

 apice late emarginatre, intus unideiitatse. Maxilla bilobiB : lobo externo palpiformi biarticulato : 

 interna acuto incurvo, ad apicem uucinato, intus ciliato. Palpi articulo ultimo elongato robusto 

 subtruncato. Mentum traiisversum, aiitice profunde emargiuatum et dente medio brevi acuto 

 instructum. Liyula subquadrata. Pedes natatorii : tarsis anterioribus 4-articulatis, in maribus 

 articulis tribus dilatatis ; posticis 5-articiilatis : unguiculis omnibus aequalibus mobilibus. 



The minute size of the Hydropori, added to then- foui- anterior tarsi being 

 quadi'iarticulate, will, apart fi-om minor characters, at once distinguish them fi-om 

 the members of the aUied groups. Up to the present period, but two represen- 

 tatives of this large genus have been detected in Madeu-a, which, for an island 

 abounding with streams, and in a genus so widely distributed and extensive, is 

 somewhat remarkable. It may be indeed that the excessive rapidity of the 

 torrents, which arc constantly liable, from the hea^-y rains, to overHow then- 

 limits and to precipitate then* contents on to distant and isolated spots (which 

 quickly afterwards, either by evaporation or absorption, become di'y), is anything 

 but favourable to aquatic life ; but whether such be the case or not, it is certain 

 that the Hydradephaga are extremely scarce. 



68. Hydroporus vigilans, Woll. 



H. oblongus subdepressus fusco-piceus, capitc, prothorace, elytrommque liueis inteiTuptis, plus 



muiusve rufo-testaceis, antennis pedibusque pallido-ferrugineis. 

 Long. Corp. lin. 2i-2|. 



Habitat in rivulis Maderse, praesertim per regiones superiores, toto anno \'ulgaris. 



H. 



oblong, somewhat depressed, dark brownisb-piceous ; the males shining, the females opake. 

 Head and prothorax i-ufo-testaccous ; i\\c former large, and more or less dusky about the region 

 of the eyes ; the hitter regularly and equally rounded at the sides, being broadest in the middle, 

 distinctly punctured along its anterior and posterior margins, and with a narrow transverse 

 portion before and behind (and occasionally the disk also) more or less cloudy or infuscate. 



