The relationship between the palaearctic and nearctic faunas 



Haliplidae 



Halipliis fulvus F. (excl. lap- 

 ponum Thorns.) .... 



Dytiscidae 



Agabus congener Payk. (coll.) . 



A. moestus Curt 



A. solieri Aube 



Colymbetes dolabratus Payk. . 

 Deronectes miiltilineatus 



Falkstr 



Hydroporus erythrocephalus L. 



H. lapponum Gyll 



H. melanocephalus Mrsh. . . 



H. memnonius Nic 



H. nigrita F 



H. palustris L 



H. polaris Fall 



H. pubescens Gyll 



Gyrinidae 



Gyrinus opacus C. R. Sahib. 



Hydrophil tdae 



Anacaena globulus Payk. . . 

 Cercyon litoralis Gyll. . . . 

 Helophorus aquaticus L. . . 

 H. arcticus Brown . . . . 



H. brevipalpis Bed 



H. flavipes F 



Megasternum boletophagum 

 Mrsh 



Liodidae 



Hydnobius punctatiis Sturm 



Scy dtna enidae 



Stenichmis collaris M. & K. 



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9 10 II 



m ! + 



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+ i + 



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— b 



- (+) 



- (+) 



+ — 



259 



be 



( + ) 



prothorax, more pronounced in the North American material, is a variable character even 

 within geographically limited populations. 



2. For the taxonomy of Atheta hyperborea Brd. and islandica Kr., vide Brundin (1943, 



P- 15-19)- 



3. Boreaphilus nearcticus Blair. Two ? ? from Baffin Island (Mus. Ottawa) were cornpared 

 with the original specimens oi nordenskioldi Maklin (1878, p. 25; 1881, p. 42) from Siberia, 



