546 MR. J. S. HUXLEY ON THE 
their ruffs down, and drifted slowly apart. When they were 
separated by about twenty yards the cock dived and came up 
close to the hen, upon which the pair began shaking once more. 
After a very few shakes they stopped, the cock put his crest down 
and swam off at a moderate pace ; the hen, however, stayed where 
she was and kept her crest up. When the male was about forty 
yards off, he went into the cat-position: on looking at the hen, 
I saw that she had done the same, with wings fairly well arched. 
The cock had at first scarcely arched his wings. but when the hen 
went into position, up went his wings to the full for an instant. 
It was but an instant, for then he dived; ‘‘a ripple was seen 
coming quickly towards the hen along the surface of the water 
(most exciting!)”; when it had nearly reached her, the 
cock appeared, slowly erecting himself out of the water in the 
usual way. He seemed to be facing her all the time. He 
settled down, and a very long shake began. There was no 
habit-preening for the first ten or a dozen shakes, nor very much 
at any time. Eventually they drifted apart, put their ruffs 
down, and did nothing in particular for the five minutes or so 
1 went on watching. 
This shows again that courtship-diving may take place apart 
from the cat-position or from weed-fetching ; and also that, 
although the cat-position seems usually to be employed as a 
stimulus to induce a bird of the opposite sex to do the Penguin- 
dive, yet the diving bird, too, may go into the same attitude 
before it dives. 
5. April 12. 8.50 a.m. 
A cock flew over from another reservoir and alighted near a 
hen. In under a quarter of a minute they had begun 
shaking. They only shook seven or eight times, with habit- 
preening, and then drifted apart. Soon the cock dived; the hen 
kept her ruff up, but the cock had dived away from her, and 
appeared a long way off. On seeing this, the hen lowered her 
crest. 
This seems to show that when one bird dives, and dives deep 
so as to produce no ripple on the surface, the other is left in a 
state of suspense which is exciting enough to make it keep its 
crest up. : 
Whether the two birds were a paired couple or not could 
only have been proved by further watching; but I should say 
that they probably were not a pair, but that their close 
proximity and the absence of their real mates excited them. The 
emotion found expression in the usual actions, but then the 
strangeness of the hen proved unsatisfactory to the cock. 
6. April 16. a.m, A pair. 
I caught them shaking. After 6 or 7 shakes they separated ; 
when they were some way apart, the hen went into a feeble cat- 
