70 Miscellaneous. 
to convince arachnologists that the inconstancy of a generic character 
is no reason for not relying upon it, his plan evidently being to 
regard as monstrosities all specimens which do not answer to the 
generic diagnosis. 
On the Influence of the Marine Currents in the Geographical Distri- 
bution of the Amphibious Mammalia, and particularly of the Eared 
Seals. By M. KH. L. Trovessarr. i 
In a memoir recently presented to the Academy Prof. Milne- 
Edwards has demonstrated the influence of the antarctic currents on 
the geographical distribution of the Penguins. By applying the same 
laws to the class Mammalia, and more particularly to the group of 
the Otaries (or seals with external ears), which have a mode of life 
analogous to that of the penguins, I have arrived at some very im- 
portant results, which confirm, in the most complete manner, the 
views put forward by M. Milne-Edwards. 
The Eared Seals, in the present geological epoch, seem, like the 
penguins, to be native to the Antarctic lands, whence they have 
spread towards the north. Carried by the blocks of ice which the 
regular currents detach every year from the great southern glacier, 
these animals have colonized the shores of Cape Horn, the Falkland 
Isles, the Cape of Good Hope, Kerguelen Island, New Zealand, 
and Australia—in one word, all lands situated in the south of 
the New and the Old Worlds. Humboldt’s current, in the west, has 
carried them, like the penguins, as far as the Galapagos Islands, 
under the equator; but while this extreme limit has not been 
. passed by the penguins, the eared seals, on the contrary, have pene- 
trated into the northern hemisphere. ‘They are found on the shores 
of California and in the north of the Pacific Ocean; but they have 
certainly not arrived there by the direct route; for these animals 
are absolutely unknown on the west coast of America, from Peru to 
the north of Mexico—a stretch of more than 20 degrees ; and, be- 
sides, the Otaries of the Galapagos Islands and those of Califorma 
belong not only to different species, but to different genera. 
This peculiarity seems at first sight inexplicable; but if we note 
on a good map of marine currents, and according to the method 
introduced by M. Milne-Edwards, all the stations where eared seals 
have been observed, we can easily explain the route followed by 
these animals before reaching the northern part of the Pacific. It 
is not the too great temperature of the tropical regions, as might be 
supposed, but the presence of contrary currents, that has banished 
them from these regions. 
The equatorial current of the Pacifie Ocean north of the Gala- 
pagos Islands, and that of the Atlantic north of the Falkland Islands, 
are directed precisely in opposition to the migrations of the Otaries. 
Those of these animals which, having reached the island of Tristan 
d’Acunha, have then tried to gain the western coast of Africa, have 
been seized by this current and driven to the west, onto the coast 
of Patagonia. 
