352 On Aquatic Carnivorous Coleoptera or Dytiscide. 
266. Hydroporus saucius, Desb. Mitt. Schweiz. ges. ILI, p. 338.—Ovalis, nigri- 
cans, thorace in medio elytrisque maculis parvis externis testaceis, pedibus fuscis, 
antennarum basi dilutiore ; elytrorum lateribus distincte curvatis ; coxis pos- 
terioribus medio sparsim fere fortiter punctatis ; elytris dense subtiliter punctatis. 
Long. vix 2, lat. 1 m.m. | 
Very closely allied to Bidessus coxalis and probably only a variety of it, but 
rather larger and darker in colour, so that the pale marks on the elytra have 
nearly disappeared. . 
Corsica. 121. 
267. Hydroporus minutissimus, Germ., M.C.—Angustulus, suboblongus, tes- 
taceus, subtus leviter infuscatus, prothorace basi medio elytrisque fasciis transversis 
nigris, elytrorum lateribus sat curvatis; coxis posterioribus medio crebre subtiliter 
punctatis ; elytris dense subtilissime punctatis. Long. 13, lat. 1 m.m. ; 
T have from Switzerland a pale variety which in some respects is intermediate 
between this and Hydroporus delicatulus. 
In Corsica there occurs a dark variety with the black marks of the upper surface 
much extended. 
Europe, from South of England to Algeria ; Corsica, and Canary Islands. 122. 
268. Hydroporus delicatulus, Schaum, Stet. Zeit., 1844, p. 198.—Elongatus, 
ancustus, depressus, testaceus, elytris fasciis transversis fuscis; elytrorum lateribus 
vix curyatis ; coxis posterioribus medio crebre subtiliter punctatis ; elytris omnium 
dense subtilissime punctatis. Long. 1%, lat. § mm. 
Very closely allied to Hydroporus minutissimus but rather smaller, narrower, 
and paler in colour, with the punctuation of the coxe and elytra a little finer ; the 
bagal fascia of the elytra indistinct: it is possible that in Switzerland specimens 
may be found to connect these two forms. 
Schaum did not distinguish Bidessus coxalis from this and the preceding species, 
and consequently considered Hydroporus minutissimus as an intermediate form of 
Bidessus coxalis and Hydroporus delicatulus. 
Europe, (Germany). 123. 
Group 5. (A. Each wing-case with a sutural stria). 
269. Dytiscus geminus, Fab., Hydroporus geminus, M.C_—Niger, vix nitidus, 
thorace in medio rufescente, elytris testaceis plaga magna irregulari nigra; thorace 
sparsim subtiliter punctato : elytris crebre subtiliter punctatis, et pubescentibus, 
