448 On Aquatic Carnivorous Coleoptera or DytiscidcB. 



C. 



529. Dytiscus alpinus, Payk., Hydropoinis alpmus* M.C. — Elongato-ovalls, sine 

 pubescentia, subopacus, subtus niger, supra testaceus, elytris nigro-lineatis ; 

 prothorace angulis posterioribus obtuse recti?, utrinque striga sublaterali \ aide 

 abbreviata, basi versus angulos posteriores leviter rugulosa ; corpora subtus 

 impunctato. Long. 5, lat 2§ m,m. 



Mas, tarsis anterioribus et intermediis leviter dilatatis, elytrorum apicibus 

 simplicibus. 



Fern., 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, Lee, 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. 21 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, el}i,ris lineis et maculis plus minusve distinctis nigris, 

 punotis sparsis minus distinctis : prothorace angulis posterioribus obtuse rectis, 

 utrinque striga sublaterali anterius et posterius abbreviata ; corpore subtus fere 

 impunctato. Long. 4l, 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, Albertrille, Germany, Aiistria, 

 Illyria. 231. 



* Hypbydrus borealis, Gyll., is considered to be a variety of tbis species ; but Hydroporus borealis, Aube, 

 is a synonym of H. da%"isii. 



