4. The death rate among young fur seals, especially among the pups, is very great. While the loss among the pups prior to their departure from the islands has been found in the past two years to approach twenty per cent of the whole number born, and though the rate of subsequent mortality is unknown, we may gather from the number which return each year that from one half to two thirds have perished before the age of three years--that is to say, the killable age for the males and the breeding age for the females. The maximum and minimum figures here represent a division of opinion. The larger figure of two thirds would even seem to be a conservative estimate. The birth rate of 1897, as we know from close estimate, was approximately 130,000; it must have been greater in 1894, approaching 200,000. From this larger birth rate only about 20,000 males survived (the quota of 1897). There was doubtless a like number of females, the sexes being equal at birth and subject to like causes of natural loss. This gives a total of 40,000 in all, out of a birth rate of 200,000, which survived to the age of three years. This is one fifth, and it is evident that the mortality exceeds rather than falls below the maximum of two thirds. 5. The chief natural causes of death among pups, so far as known at present, are as follows, the importance of each being variable and more or less uncertain: _a._ Ravages of the parasitic worm _Uncinaria_; most destructive on sandy breeding areas and during the period from July 15th to August 20th. _b._ Trampling by fighting bulls or by moving bulls and cows, a source of loss greatest among young pups. _c._ Starvation of pups strayed or separated from their mothers when very young, or whose mothers have died from natural causes. _d._ Ravages of the great killer (_Orca_), known to be fatal to many of the young, and perhaps also to older seals. At a later period drowning in the storms of winter is believed, but not certainly known, to be a cause of death among the older pups.