September.
Straits of Malacca 3° N. (146)
Indian Ocean 15° S.? (123)
Suppose that some individuals in the Atlantic migrate towards the south
beyond the latitude of the Cape of Good Hope and get much farther than
20° eastern latitude, they will come into the Indian Ocean. I think
that when these individuals returning to the north, find themselves
checked by the continent of Asia, they will swim in any direction, and
that perhaps most of them will find back the outlet round the Cape of
Good Hope or south of Australia, so that in such cases individuals will
be met with in the South Atlantic, or in the South Pacific, at times
that one would not expect to find any.