FAUNA OF THE BANKS. 337 



to a district north of the yearly isothermal line of 32°, 

 which thus includes the Arctic-American Archipelago, 

 northern Greenland, Spitzbergen, Nova Zembla, and 

 the coast of Siberia. This is a true circumpolar fauna, 

 and can scarcely be said to be Asiatic, European, or 

 American, though members of the group extend in di- 

 minished numbers and size down on the Asiatic coast, 

 to Japan, as we are informed by Dr. W. Stimpson and 

 by P. P. Carpenter in the Report of the British Associ- 

 ation for 1856 ; on the European coast as far as the 

 Mediterranean Sea, and on the eastern American coast 

 as far as New Jersey, where the polar currents give, at 

 great depths, the necessary amount of cold for their ex- 

 istence. South of this circumpolar belt is a sub-arctic 

 zone of life corresponding to the yearly isothermal of 

 40°. This line starts from near Cape Breton in North 

 America, and includes Iceland, the Hebrides, the Faroe 

 Islands, Finmark, and northern Norway. On the 

 American coast this fauna is characterized by a small 

 number of species not yet recorded as found in the cir- 

 cumpolar district, which only occur southward in the 

 Acadian district in diminished numbers and impoverished 

 in size. This Syrtensian fauna bears the same relations 

 to that of the Acadian district as that of Finmark (judg- 

 ing from the data furnished us in the papers of Professor 

 Sars) does to that of the Baltic, North, and Scottish 

 Seas, the boreal or Celtic fauna of Forbes, and which is 

 the European representative of the Acadian fauna. We 

 have shown* that this fauna is limited to Hudson's Bay, 

 the coast of Labrador, and the northern coast of New- 



* Canadian Naturalist and Geologist, Dec, 1863. See also the Proc. Bost. 

 Sue. Nat. Hist., Jan. i866, p. 276. 



