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6 MARINE ANIMALS UNIMPORTANT IN GEOGRAPHY. 
ally to foreign markets not less than 20,000,000 squirrel skins, 
Great Britain has sometimes imported from South America 
600,000 nutria skins in a year. The Leipzig market receives 
annually nearly 200,000 ermine, and the Hudson Bay Company 
is said to have occasionally burnt 20,000 ermine skins in order 
that the market might not be overstocked. 
Of course natural reproduction cannot keep pace with this 
enormous destruction, and many animals of much interest to 
natural science are in imminent danger of final extirpation.* 
Large Marine Animals relatively unimportant in Geography. 
Vast as is the bulk of some of the higher orders of aquatic 
animals, their remains are generally so perishable that, even 
where most abundant, they do not appear to be now forming 
permanent deposits of any considerable magnitude; but it is 
quite otherwise with shell-fish, and, as we shall see hereafter, 
with many of the minute limeworkers of the sea. There are, 
on the southern coast of the United States, beds of shells so 
extensive that they were formerly supposed to have been 
naturally accumulated, and were appealed to as proofs of an 
elevation of the coast by geological causes; but they are now 
ascertained to have been derived chiefly from oysters and other 
shell-fish, consumed in the course of long ages by the inhabitants 
of Indian towns. The planting of a bed of oysters in a new 
locality might very probably lead, in time, to the formation of 
a bank, which, in connection with other deposits, might per- 
ceptibly affect the line of a coast, or, by changing the course of 
marine currents, or the outlet of a river, produce geographical 
changes of no small importance. 
* Objectionable as game laws are, they have done something to prevent the 
extinction of many quadrupeds, which naturalists would be loth to lose, and, 
as in the case of the British ox, private parks and preserves have saved other 
species from destruction. Some few wild animals, such as the American mink, 
for example, have been protected and bred with profit, and in Pennsylvania 
an association of gentlemen has set apart, and is about enclosing, a park of 
16,000 acres for the breeding of indigenous quadrupeds and fowls. 
