450 On Aquatic Carnivorous Coleoptera or DytiscidcB. 



D. 



534. Dytiscus lepidus, Oliv., Hydroporus lepidus, M.C. — Species pervariabilis. 

 Ovalis, convexus, posterius acurainatus, nigricans, prothoracis lateribus testaceis, 

 autennis pedibus elytrisque colore variabilibus, his semper picturatis ; protborace 

 versus latera striola indistincta ; corpore subtus evidenter coriaceo, coxis posteriori- 

 bus, sparsim subobsolete punctatis. Long. 3, lat. 1| m.m. 



This is a most variable species, the elytra are sometimes largely black, with the 

 lateral border and some very irregular waved marks yellowish ; at other times 

 they are yellow, wnth the suture, a large transverse patch on the middle, and a 

 humeral dot black ; all variations occur between these extremes ; the punctuation 

 varies very much, from a rather close but somewhat indistinct sculpture, to an 

 obsolete one in which the elytra appear nearly smooth. Hydroporus rufulus, Aube, 

 is founded on individuals in which the general colour is obscure reddish, the marks 

 of the elytra being ill-defined. The smoother and paler forms occur only in the 

 southern part of the area of distribution of the species. The sexes are scarcely 

 distinguishable. 



Hydroporus optatus, Wehncke, is I consider a variety of this species. 



Western Europe and Northern Africa ; widely distributed but apparently wanting in Eastern Europe. 

 Scotland, England, France, Spain, Portugal, Corsica. 320. 



53.5. Hydroporus formosus, Aube, M.C. — Oblongo-ovalis, convexus, posterius 

 acuminatus, crebre distincte punctatus, tenuiter pubescens, nigricans, antennis, 

 pedibus, prothoracis lateribus elytrisque testaceis, his sutura, fasciis transversis 

 undatis maculaque humerali nigris ; prothorace utrinque striola indistincta ; corpore 

 subtus subopaco, minus distincte coriaceo, coxis posterioribus abdomineque basi 

 utrinque fortiter punctatis. Long. 31, lat. 2 m.m. 



This species is extremely similar to some of the varieties of Dytiscus lepidus, 

 but is a little more elongate and is readily distinguished by the coarse punctures 

 of the under surface : a large series of specimens might possibly I think show it 

 to be an extreme form of that variable species. The sexes appear to be scarcely 

 distinaruishable. 



o 



Algeria, Tangiers, Tripoli. 321. 



536. Hydroporus escheri, Aube, M.C. — Oblongo-ovalis, convexus, sat nitidus, 

 sat crebre et subtiliter punctatus, tenuissime pubescens, nigricans, antennis 

 pedibusque testaceis, prothorace rufo, anterius et posterius nigricante, elytris 

 maculis vel signaturis testaceis ; thorace utrinque striola minutissima ; corpore 

 subtus sat evidenter coriaceo, coxis posterioribus fortiter punctatis : abdomine 

 ssepius rufescente. Long. Z\, lat. 2 m.m. 



