98 IXSECTA MADERENSIA. 



confined to high altitudes. The only tlu'ee specimens which I have seen were 

 captured by myself, on the 19th of July 1850, in the bed of a smaU trickling 

 stream Avhich issues out of the rocks at the extreme head of the Ribeu'O de Joiio 

 Delgada. 



Genus 35. PHILHYDRUS. 



Solier, Ann. Je la Soc. Ent. de France, iii. 315 (1834). 



Corpus fere ut in Hydi-obio, sed luajoris magnitudinis et luinus convexum; alls amplis; palpis 

 maxillaribus longissimis gracilioribus, articulo ultimo penultimo bre^dore. 



Fhilhydriis is sometimes regarded as a section of the last genus ; but it 'oould 

 appear to have as great a claim for isolation as at any rate many other gi'oups 

 which are universally received. It differs from Sydrobms in the less convex form 

 of the insects which compose it, and in the much greater length of their maxillary 

 palpi, — which are slender, and have the terminal joint always shorter than the 

 penultimate one. In the ^Madeira Islands, moreover, the great disparity of size 

 between the single representatives of each genus wiU serve additionally to di- 

 stinguish them. 



77. PMLhydrus melanocephalus. 

 P. ovalis nitidus niger, supra fusco-testaceus, capite posticc nigricanti, prothorace in discum plus 

 rainusvc obsolete infuscato, clytro singulo stria suturali postica impresso ct plaga parva basali 

 obscura longe intra huuierum sita nigrcscente ornato, tibiis tarsisque piccscenti-ferrugineis. 

 Var. /3. supra late nigrescens, limbo solo obscure pallidescenti. 

 Long. Corp. lin. 2\-^. 



Ht/drophilus melanocephalus, Oliv. Ent. iii. 39. 14 (1795). 



, GyU. Im. Suec. i. 119 (1808). 



Hydrohius melanocephalus, Ericli. Eiif. der Mark Brand, i. 209 (1837). 

 Philhydrus melanocephalus, Mulsaut, Palp. 137 (IS 14). 



Habitat Portum Sanctum : in ri\'ido quodam parvo Ribeiro de Serra de Fora dicto, lapidibus adhae- 

 rentem, Aprili exeunte a.d. 1848 copiose collegi : iu Madera propria mihi adhuc non obvius. 



P. oval, rather convex (though depressed compared with the H. conglobatus), and shining ; most 

 minutely and closely punctiu'cd all over ; piceous-black. Head with a large subtriaugidar patch 

 in front of each eye paler. Prothoraa: and elytra brownish-testaceous ; the former generally more 

 or less obsoletely infuscatcd on its disk, slightly punctured in front of its posterior angles, and 

 with an impressed point on either side of its disk behind ; the latter with just perceptible indica- 

 tions (under a high magnifying power) of punctured striic, but with a deep sutural one on each 

 behind, with a small obscure dash at the extreme base of each, rather nearer to the shoulder than 

 to the suture, and occasionally a still fainter and more elongated one close to the shoulder itself, 

 more or less dusky-black. Femora piccous ; tibia, tarsi, palpi and antenna rufo-ferruginous ; 

 the first two more or less picescent. 

 Var, fi. with the entire upper disk darkly and broadly infuscatcd, or almost black, — the patches in 



