INSECTA MADERENSIA. 87 



Elytra with a few faint, irregular, interrupted longitudinal lines dull testaceous ; and with three 

 longitudinal rows of impressed points on each,— the two inner ones of which are distinct, and 

 disposed in depressed stria;, whilst the outer one is almost obsolete. Prothorax beneath, legs, 

 antenna, and parts of the mouth pale ferruginous. 



A rather coiiimon Si/drojoonis in nearly all the streams of Madeira, above the 

 altitude of 1000 feet ; and on the northern side of the island descendinar to a much 

 lower elevation. In the Ribeiro de Santa Luzia, and at the Cui-ral das Romeii-as, 

 above Punchal, I have observed it in great profusion ; and in the rivulets issuing 

 from the Paul da Serra it is equally abundant. Its normal range however would 

 appear to be from about 2000 to 3000 feet above the sea. Near Sao Vincente 

 indeed I have eaptm-ed it, occasionally, on the level of the shore ; but, like the 

 Agabus Maderensis with which it was found in company, it is possible that such 

 specimens had descended from the lofty ravines above, which terminate at that 

 particular point, as indeed they do ahnost everywhere along the northern coast, in 

 abrupt sea cliffs, over which the mountain torrents pour in constant waterfalls. 

 In such positions it is clear that insects of a normally higher range might, and in 

 all probability would, be continually washed down, — especially dm-ing the severe 

 floods to which the island is subject, — and so become naturalized below. 



69. Hydroporus confluens. 

 H. ovatus nigi-o-piceus, supra flavus capite postice leviter infuscato atque elytris apicem versus lineis 



interruptis nigris ornatis, antennis pedibusque testaceis. 

 Long. Corp. lin. 1^. 



Bytiscus conjluens, Fab. Ent. Syst. i. 198 (1792). 

 Hyphydrus confluens, GyU. Ins. Suec. i. 522 (1808). 

 Mygrotus conflttens, Steph. III. Brit. Ent. ii. 47 (1828). 

 Hydroporus confluens, Aube, Hydrocan. 557 (18.38). 



Habitat Maderam australem, rarissimus : in stagno quodam parvo baud procul ab urbe Funchalensi 

 sito exemplar unicum nuperrime collegit Dom. Rousset. 



H. ovate, shining, beneath piceous-black, above pale yellow. Head of a deeper yellow than the rest 

 of the surface, being almost testaceous ; dusky behind, and about the region of the eyes. Pro- 

 thorax very short and small, narrower than the elytra, being attenuated in front, and with the 

 sides (though oblique) straight ; punctured before and behind. Elytra exceedingly pale, with 

 the suture, and four irregular lines towards the apex of each, deep black, — of which the one 

 nearest to the suture is short ; the second longer, extending to a little before the middle ; the 

 third somewhat shorter than the first ; and the fourth long but broken, the lower portion beino- 

 contluent with the third, and the upper (which in the common European type is well-defined, 

 and only just detached) almost obsolete, being merely indicated by a minute dash considerably 

 in advance of the former : with two or three longitudinal rows of impressed points (disposed in 

 strise) on each, and some large scattered puiictui-es about the region of the suture. Lens and 

 antennce pale testaceous. 



