448 On Aquatic Carnivorous Coleoptera or Dytiscide. 
C. 
529. Dytiscus alpinus, Payk., Hydroporus alponus,* M.C.—Elongato-ovalis, sine 
pubescentia, subopacus, subtus niger, supra testaceus, elytris nigro-lineatis; 
prothorace angulis posterioribus obtuse rectis, utrinque striga sublaterali valde 
abbreviata, basi versus angulos posteriores leviter rugulosa; corpore subtus 
impunctato. Long. 5, lat 23 m.m. 
Mas, tarsis anterioribus et intermediis leviter dilatatis, elytrorum apicibus 
simplicibus. 
fem., elytrorum lateribus versus apicem angulariter prominulis, apicibus sub- 
truncatis. 
Lapland and Norway : extends to 68° 10’ according to Sahlberg ; Arctic Siberia. 238. 
530. Hydroporus duodecimlineatus, Lec., M.C.—Ovalis, sine pubescentia, sub- 
opacus, subtus niger supra testaceus, elytris nigro-lineatis; prothoracis angulis 
posteiioribus fere rectis, utrinque striga sublaterali valde abbreviata ; corpore 
supra et infra fere impunctato. Long. 4, lat. 2? m.m. 
Mas, tarsis anterioribus et intermediis bene dilatatis, elytrorum apicibus simpli- 
cibus. 
Fem., elytrorum lateribus versus apicem obtuse prominulis, apicibus emarginatis. 
This species is very closely allied to Dytiscus alpinus, but is smaller and of a less 
elongate form ; it should in my opinion be considered a distinct species till inter- 
mediate specimens are found. 
North America ; (Lake Superior). 239. 
531, Hydroporus davisii, Curt., M.C.—Oblongo-ovalis, sine pubescentia, subopacus, 
subtus nigricans, supra testaceus, vertice plaga obliqua utrinque prothoraceque 
medio plus minusve infuscatis, elytris lineis et maculis plus minusve distinctis nigris, 
punctis sparsis minus distinctis: prothorace anegulis posterioribus obtuse rectis, 
utrinque striga sublaterali anterius et posterius abbreviata; corpore subtus fere 
impunctato. Long. 43, lat. 2 m.m. 
In the male the front and middle tarsi are a good deal dilated, and the claws of 
the front ones are more elongate than in the female. 
This species varies much as to distinctness of the lines and markings, and also 
as to the colour of the under surface. 
Europe : in very clear waters ; Finland, Scotland, Pyrenees, Reynosa, Albertville, Germany, Austria, 
Illyria. 231. 
* Hyphydrus borealis, Gyll., is considered to be a variety of this species ; but Hydroporus borealis, Aubé, 
is a synonym of H. davisu. 
