On Aquatic Carnivorous Colcoptera or Dytiscida. 457 



This is a variable species in size and sculpture, and even in form : some individuals 

 are quite dull, and others shining ; the more shining individuals are usually more 

 convex and more distinctly, but not more closely punctured ; generally the elytra 

 and thorax form an almost continuous outline, but in the more convex individuals 

 this outline is a little more interrupted. The sexes are difficult to distinguish, but 

 the basal joint of the front and middle tarsi is distinctly larger in the male. 

 Hydroporus monticohx, Sharp, was described from small, dull, and finely punctured 

 individuals of this species. 



Northern Europe, and Arctic Siberia; from 67° 20' North (Sahlberg) to Geneva. 



556. Hydroporus cantabricus, n. sp. — Ovalis, latiusculus, fere sine pubescentia, 

 sat nitidus, piceus, vel ferruginous ; antennis pedibusque rufis ; prothorace disco 

 sparsim subtiliter punctate, limbo distincte punctato ; elytris crebre evidenter 

 punctatis ; coxis posterioribus sparsim fortiter jDunctatis. Long, oh, lat. vix 2 m.m. 



This species comes very close indeed to some of the more shining varieties of 

 Hydroporus melanarius, but I have not been able to connect it with them at present ; 

 the elytra have the punctures more numerous, and their junction with the thorax 

 forms a less indistinct angle, the colour, (especially of the head and thorax), is paler 

 in all the specimens. 



Europe, (Reynosa). 395. 



557. Hydroporus insularis, n. sp. — Oblongo-ovalis, sat convexus, fere sine pubes- 

 centia, piceus, prothorace lateribus late dilutioribus, antennis pedibusque rufis; 

 abdomine pectoreque nigris; prothorace medio sublsevi, limbo minus punctato; 

 elytris sat crebre subtiliter punctatis ; coxis posterioribus sparsim fortiter punctatis. 

 Lons:. 3l, lat. 2 m.m. 



Mas, pernitidus, tarsis anterioribus et intermediis articulo basali magno. 



Fern., omnino opaca. 



This species is much smaller than Hyphydrus memnonius, and is more finely 

 jDunctured, in other respects it is extremely similar ; of the few specimens I have 

 seen all the females are ojjaque : the basal joint on the intermediate tarsus of the 

 male is larger than in Hydroporus revelierei. 



Corsica. 393. 



558. Hyphydrus memnonius, NicoL, Hydroporus memnonius, M.C. — Oblongo- 

 ovalis, minus convexus, fere sine pubescentia, piceus, prothorace lateribus late 

 dilutioribus, antennis pedibusque rufis, illis sat elongatis, abdomine pectoreque 

 nigris ; prothorace antrorsum minus angustato, medio sparsim subtiliter, limbo 



