GEOGRAPHICAL DISTRIBUTION OF ANIMALS. 21 
equator and back again without leaving some traces behind 
them. Nor are the faune of the arctic and of the antarctic so 
closely allied as has sometimes been supposed. There is no 
well-authenticated instance of the same animal species occur- 
ing in each of the frigid latitudes, except such as have an 
intermediate or cosmopolitan existence.* 
As Dr. Packard} has shown, the submerged beaches give 
very good evidence that the boreal and arctic regions of 
North America during the true Glacial epoch, stood at a 
much higher level above the sea than at present. This ele- 
vation was undoubtedly enough to raise the submerged bor- 
der of the continent, the Gulf of St. Lawrence, the Banks 
of Newfoundland, and the banks off the coast of Nova Scotia, 
Maine, and Cape Cod, above the sea-level. As the rise and 
enlargement of the lands at the north during the Tertiary pe- 
riod had changed the climate of Europe and the northern parts 
of North America from tropical to temperate, this elevation 
during the Glacial epoch must have changed the climate of 
these regions from temperate to frigid, and brought the snow 
line down to the coast of New England. Such an enlarge- 
ment of lands at the north would not, however, change 
materially the climate of the tropics, and it is altogether 
probable that the Gulf Stream flowed on and warmed the 
southern coast as it did in the Tertiary and does now, and 
that the coral reefs of Florida and the West Indies were then 
slowly building beneath its warm waters. 





* Professor Lilljeborg, in a recent paper (noticed i in the NATURALIST, p. 48), in the 
Trans. Scientific Soc. at Upsala, on Lysianassa Magelianica Milne Edwards, and 
n some other Crustacea of the sabondar Amphipoda, on the opar of Sweden and | one 
way, — admitmg that ao species had fodca y 
o have discovered, in 
phipod living upon the sept es Norw rwegian pian the Lysianassa Sie poneniae of 


Milne Edwards. Bate nt wn, however, in the ZoUlogical Record for 1865, p. 330, 
that the arctic species i ag only specifically distinct from the Zysianassa of Milne 
Edwards, but that it cannot be yeferred oe that ena er facts show how very diffi- 
without a direct 

careful c comparison of specimens, and ee ‘ae pn can be placed in the 
asi seerd a such animals 
t Observ n the Glacial Phenomena of Labrador “an Maine. Memoirs Boston 
Soc. Nat. Meg vai I, Part II. Many of the facts, on several succeeding pages, are 
drawn almost wholly from this very interesting paper. 
® 
