Handbook of Paleontology 87 



of northerly and easterly winds, hosts of creatures that 

 make their home in the cold arctic waters appear there. 

 Both on the eastern and western coasts of North America, 

 in the more northern waters are species that have been 

 distributed by way of the arctic regions and that also 

 occur on the northern coasts of Europe. Cape Cod, in 

 general, marks the most southern extension of the arctic 

 fauna and the most northern extension of the southern 

 forms. The cold Arctic Current creeps down the New 

 England coast to Cape Cod, but south of this point, dur- 

 ing the summer the shore is warmed by drift from the 

 Gulf Stream. The Kuroshiwo or Japan Current of the 

 Pacific has the same effect on the west coast as the Gulf 

 Stream on the east. There are exceptions, of course, to 

 this distribution of arctic and southern forms. For in- 

 stance, there are a number of animals which have their 

 true home south of Cape Cod that are found around Cape 

 Breton and Nova Scotia where the waters at the mouth 

 of the Gulf of St Lawrence are warmed by the last ap- 

 proach of the Gulf Stream to the coast at this place before 

 it is finally deflected into the midst of the Atlantic. It is 

 also true that animals that find their natural habitat in 

 the cold waters of the shore farther north are likewise 

 found in the deeper, and therefore colder waters farther 

 south. Certain forms that are found in the shallows of 

 the Maine coast live only in the deep, cold waters south 

 of Maine. One should not assume, either, that animals 

 become rare or even small in number as they reach the 

 limit of their range. The Common Scallop (Pecten) is 

 an example of a form that occurs in large numbers close 

 to the limit of its range, for it is very abundant in Pro- 

 vincetown Harbor, Cape Cod, and is almost unknown 

 north of Cape Cod. 



