1865.J PACKARD — ON DRIFT PHENOMENA. 443 



very distinct fades. It is evident that on each side of the Atlan- 

 tic, the same faunal distinctions obtained during this period as 

 now. There was, however, a greater range in space of purely 

 Arctic species, and, though the European marine fauna was much 

 more closely allied to our own, owing to the great predominance 

 of exclusively Arctic forms, it is yet evident that the Arctic glacial 

 fauna was divided into a Scandinavian district, and a Labrador 

 district, each the metropolis of a small number of species peculiar 

 to itself and limited to its area. 



The assemblages found at various points along the coast from 

 Labrador to Maine are not the exact equivalents of the present 

 faunae. They differ in containing a very small percentage of 

 extinct species, and in a different grouping of species still living. 



Thus, in the Labrador beds are several species of Fusus 

 which differ from recent Arctic forms, and also a species of Beta ; 

 certain forms, such as Panopoea and perhaps Cyrtodaria, which 

 were abundant formerly, seem to be dying out at the present day. 

 In Maine the change is still more marked. Thus, the most char- 

 acteristic shell of the marine clays is Leda truncata (PorilandiccC) > 

 which has wholly disappeared from the seas south of the circum- 

 polar regions, unless future deep-sea dredging reveals its presence 

 in some of the abysses off our coast. An undescribed Macoma 

 is also characteristic of the beds about Portland ; and other im- 

 portant changes have occurred in the relative abundance of 

 species, and the manner in which they are grouped as compared 

 with the present assemblages in zoological districts farther north ? 

 and similar in physical surroundings to the glacial seas. 



The Labrador district of the Arctic fauna, instead of being re- 

 stricted as now to the eastern coast of North America from the 

 Arctic archipelago to the banks of Newfoundland, and shading 

 off into the Acadian district at the present line of floating ice, 

 during the Glacial epoch extended up the St. Lawrence river, 

 and as far as Portland, on the coast of Maine, where it shaded 

 into a more southern assemblage. 



In Maine there are two distinct horizons of life. The lowest 

 and oldest is found at the bottom of the boulder-clay at high- 

 tide mark along the coast. The second horizon is composed of 

 rewashed, finely laminated, less stony clays occupying the coast 

 from 25 feet above the sea level to a height, 50 to 100 miles in- 

 land, of nearly 300 feet. The species found in this second 

 horizon are rather boreal forms than purely Arctic. In the beds 



