INSECTA MADERENSIA. 89 



Dytiscus nniator, Linn. Fna Suec. 779 (1761). 

 Oi/n'nus natator, Linn. Sysf. Nnt. 567 (1767). 



, Eab. Ent. Syst. i. 202 (1792). 



• , Aube, Hydrocan. QQi (1838). 



Habitat Maderam, niilii non obvius : exemplar unicunij a Doin. Heinecken olim captum (e.x Anglia 

 cum plantis aquaticis introductus ?) in museo Loweano vidi. 



G. ovate, black, with a slightly greenish tinge, shining. Prothorax short, produced iu the centre 

 behind; and transversely furrowed in front, especially towards the anterior angles. Elytra 

 truncated at their apex, and finely striate-punctate ; their inflexed margin (with that of the pro- 

 thorax), the breast, the apex of the abdomen underneath, and the legs riifo-testaceous. 



As just stated, it is not Avitliout hesitation that I admit the common European 

 G. natator into our present fauna : nevertheless, since there cannot be any doubt 

 that Dr. Heinecken's specimen was captured in the island, it is possible that the 

 species may be truly indigenous, although rare, and that it has hitherto escaped 

 the observation both of myself and the other naturaUsts who have been working 

 during the last few years in the Madeiran group. I tliink it far from unlikely, 

 however, that the unique example on which its admission must be considered to 

 rest may have been accidentally introduced with aquatic plants, from more northern 

 latitudes, which were formerly imported into the gardens more generally than 

 they are now by the English residents ; — -an idea which is rendered the more pro- 

 bable, since I am informed by Mr. Lowe that Dr. Heinecken's collection was 

 principally made in the immediate vicinity of Eunchal, where the fresh-water 

 tanks, attached to nearly every house, would afford ample facilities for an insect 

 like the present one to become temporarily naturalized. 



Sectio hi. PHILHYDRIDA. 

 Fam. 4. PARNID^. 



Genus 29. PARNUS. 



Pabriciua, Ent. Syst. i. 215 (1792). 



Corpus minusculum, subcylindrico-oblongum, villosum : alis amplis. Antennae 1 0-articulatae bre- 

 vissimse, articulis primo et secundo majoribus, hoc maximo extus valde producto, reliquis bre- 

 vissimis, clavam elongato-fusiformem subserratam efficientibus. Lahrum amplum transversum, 

 antiee leviter emarginatum. MandibulcB acutfe, apice dentatee. Maxilla bilobse membranacese : 

 lubo externa latiusculo : interna angusto, intus ciliato. Palpi brevissimi, articulo ultimo robusto, 

 in maxillaribus subovato, in lahialibus subgloboso. Mentum transversum, antiee leviter emar- 

 ginatum. Ligula ampla. Pedes ambulatorio-subnatatorii, graciles elongati : tibiis cylindricis 

 muticis : tarsis articulis quatuor subaequalibus, quinto longissimo. 



N 



