254 A. S. PACKARD, Jr., ON THE GLACIAL PHENOMENA 



By the foregoing lists it will be seen that during the Quaternary of the French and 

 Scandinavian geologists, or post-pliocene period of Lyell, the distribution of marine animals 

 was governed by the same laws as at the present day. In going southward from Labrador 

 to New York the seas became warmer the more they came in contact with the heated 

 waters of the Gulf Stream, whose influence was evidently exerted on the coast of New 

 England during the glacial period. The climate of New England was not purely arctic, 

 but rather sub-arctic, where now it is " boreal." While this period was characterized by 

 the wide distribution of what are now purely arctic or circumpolar species, there were also 

 intermingled boreal or Acadian forms. Thus the arctic Leda arctica, Pecten gronlandicus, 

 Serripes gronlandicus, Pandorina arenosa, and Fitsus tomatus, were then wide spread and most 

 characteristic shells from Greenland to Portland, Maine. The Leda especially, abounding 

 in every clay deposit, has now become wholly extinct south of Spitzbergen and the 70th 

 parallel of latitude. 



An exceedingly small percentage, if any, of the species has become wholly extinct, the 

 only instances occurring to us being the Beluga vermontana, about which there must be 

 great doubt, owing to the difficulty of distinguishing the fossil species of whales, and the 

 new species of Fusus (F. lahradorensis), and, possibly, Bela robusta, described above. 



A considerable number have become extinct in the north temperate seas, owing to the 

 great changes in the climatic conditions. A parallel case is shown in the southward migra- 

 tion and subsequent extinction in Europe of the musk-ox, polar bear, lemming, and other 

 quadrupeds now confined mostly within the limits of the arctic circle. 



During the glacial period, or that of the deposition of the glacial beds, (Leda clay of 

 Dawson,) which are unmistakably rewashed terminal moraines left during the incoming or 

 coldest period of the Quaternary, (when, we have every reason to believe, true glaciers of 

 great extent eroded the present river systems as far south as New York,) there was a 

 greater uniformity than now of the climate ; but yet, as shown by the distribution of ani- 

 mal life, there was a decided change from a purely arctic to a sub-arctic climate, from 

 Greenland southward. 



At present, the arctic or circumpolar fauna is restricted 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 circum- 

 polar fauna, and can scarcely be said to be Asiatic, European, or American, though members 

 of the group extend in diminished 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 

 Association 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 existence. 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 Is- 

 lands, 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 circumpolar 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, (judging from the data furnished us in the papers of Professor Sars,) 

 does to that of the Baltic, North Sea and Scottish seas, the boreal or Celtic fauna of Forbes, 

 and which is the European representative of the Acadian fauua. We have shown * that 



1 Canadian Naturalist and Geologist, Dec., 1S63. See also the Proc. Bost. Soc. Nat. Hist., Jan. 1866, p. 276. 



