28 G Ev Hl, BARRETT HAMILIOV [sULY 
ones. All around their stations were new harems, which had been 
formed by late arriving cows, attended on by bulls which had previ- 
ously possessed only a few cows each. 
At the Reef or eastern section a very similar state of things pre- 
vailed, and on the 13th July not only was the number of cows on 
shore vastly greater than on any previous occasion in that year, but 
the bulls had also increased in numbers in a manner for which, I con- 
fess, 1 was totally unprepared. 
A point which struck me very forcibly in regard to the new bulls 
on this day was that they were, in my opinion, all young bulls, that is, 
they were blacker or greyer, as well as smaller, than the bulls which 
I saw during my earlier visits to the rookery, in the centre of the 
thickest masses of females. 
The new bulls did not show the yellowish colour of the older bulls ; 
they did not accompany the old bulls to the rookery early in the 
season when they arrived to await the coming of the cows; and they 
would not at that time have dared to approach within many yards of 
these old bulls. It was evident, in fact, that, like the cows and 
bachelors, these young bulls continue to arrive at the rookery until the 
height of the season, and that they do not accompany the older bulls, 
which arrive before and await the arrival of the cows. 
I am unable to state the time at which the old bulls left the North 
rookery of Bering’s Island, for in 1896 I was not there early enough 
to recognise them individually, and it was unfortunate that in 1897 
neither Dr. Stejneger nor I were able to visit the North rookery after 
the 16th July, on which date I could recognise many of the bulls 
which I had seen on the rookery ground earlier in the season. At 
what time they took their departure it is impossible to say, but it 
seems reasonable to suppose that they did so at the same time as did 
the bulls of Copper Island, that is to say, at about the first week of 
August. 
Behaviour of the Bulls. 
The following notes will give some idea of the nature of the tasks 
which the bulls have to perform :— 
At Kishotchnaya, in the harems which I kept specially under 
observation, a large half-bull was observed in coitu at 3 P.M. on the 
29th June. Afterwards the cow and bull did not separate, but con- 
tinued to sit near each other, and at 3.55 P.M. the act of copulation 
was repeated, on this occasion in from 6 to 8 inches of water. I then 
left the rookery, and returned at 6.15 P.M. at which time I found 
(apparently) the same animals for the third time 7 coztu, on this occa- 
sion in water in which both could swim; the operation took place 
largely when the animals were floating side by side in the water. 
At about the same time (viz. 6.40 to 6.55 P.M.) another half-bull 
and cow were observed in coitw in a depth of from 2 to 3 feet of 
