Correspondence—Steller’s Sea-cow. 575 
glaciers. The Mammoth may be supposed to have passed between 
Asia and America at this time. At a later date, when Behring 
Straits were opened and the perennial accumulation of snow ceased 
on the lowlands, the clay was probably carried down from the 
highlands and deposited during the overflow of rivers. Over this 
land the Mammoth roamed, and wherever local areas of decay 
of ice arose, bogs would be produced which served as veritable 
sink-traps. The author considers it probable that the accumulation 
of ‘‘ ground-ice ”’ was coincident with the second (and latest) epoch 
of maximum glaciation, which was followed by an important sub- 
sidence in British Columbia. 
CORES} @saNED aw C221. 
THE RECENT GEOLOGICAL HISTORY OF THE ARCTIC LANDS. 
In Sir Henry Howorth’s article, bearing the above title, which 
appeared in the November Number of this MaGazing, he writes 
(at page 499), “so far as we can make out, the climate (of the 
Circumpolar Lands) has been becoming more and more severe in 
historic times, and that in the Pleistocene age, so far as we have 
evidence, the climate of the Polar area was more, and not less, 
temperate than now.” ..... “This again is confirmed by such 
facts as the occurrence of the great sea-cows, which Steller dis- 
covered around Behring’s Island, in a latitude far away from all 
their relatives and congeners. ‘They are essentially animals which 
thrive under temperate or subtropical conditions, and this colony, 
so lately occurring in the North Pacific, seems to point clearly to 
the climate of that region having been recently milder.” 
Quoting from my paper on Fossil Sirenta (Grou. Mac. 1885, 
p- 425), “Assuming, as I think we may, that the living Sirenia 
belong exclusively to the tropical regions of the earth, and that Rhytina, 
in its boreal home, was simply a surviving relic from the past, a 
sort of geological ‘outlier,’ we must conclude that the presence 
of about 12 genera and 27 species of fossil Sirenia, as widely 
distributed (over Hurope and America) then, as the recent forms 
are (within the tropics) at the present day, but with a range from the 
tropic of Cancer up to (nearly) 60° of north latitude, attests the 
former northern extension of subtropical conditions of climate which 
must have prevailed over Hurope, Asia, and North America in 
Tertiary times.” 
It seems to me that the only doubtful point is as to when and 
how long in Tertiary times this warmer condition of climate lasted. 
Nor must we omit to bear in mind that the survival of “Steller’s 
sea-cow”’ (Rhytina gigas), down to 1780, around the shores of 
Behring and Copper Islands, in 55°-60° N. latitude, is very largely, 
if not wholly, due to the “ Kuro-Sivo,” or “Black River,” the Gulf- 
stream of the Northern Pacific, which, by its warm waters, encourages 
the growth so far to the northward of those vast submarine meadows 
of succulent Algze on which these Phytophagous Sirenians subsisted. 
Nor has the changing climate or want of food caused the elimination 
