260 MK. JULIAN S. HUXLEY ON 
went right up to the nest and settled down on it. The male dozed on the 
open water with his head under his wing. It was remarkable that since the 
arrival oi: the male not a single sound had been uttered by either bird. 
About half an hour later the male flew ofE. The female continued to 
brood. At one time a Richardson's Skua came down close to the nest. This 
was the signal for the Diver to give a series of mewing calls, with neck out- 
stretched in the direction of the enemy. (Occasionally the neck may even be 
directed slightly downwards.) About 7 P.M. I went off to carry out some other 
work. On returning, she was on the tarn. I visited the nest, and found it 
a low heap of mud with a shallow depression, and a moderate amount of 
moss round the rim. There were also several pieces of slate on it, but it was 
not clear whether their presence was not purely accidental. 
On my returning to the hiding-tent, the bird soon came hack to the nest. 
At 7.45 P.M. the male came back to the tarn. The female continued to sit 
without making any sign for a few minutes, but then suddenly left the nest 
and joined the male. Both appeared excited, and " looked into the water " 
several times in quick succession. Immediately afterwards they both assumed 
a very poor " snake attitude," with the neck on\j slightly arched. This 
lasted but a short time ; the female then gave five splash-dives in rapid 
succession. The pair then indulged in a snake-ceremony, swimming towards 
me almost parallel, neither markedly leading. It was, however, a poor aifair 
compared with those at full intensity of emotion. They then swam close up to 
the moss-bank on which was the pairing-nest, the female leading ; she swam 
close in and was obviously excited, but the male did not follow. After both 
had had a spell of rest on the open water, the male looke"d up and soon 
started a "roll-growl " (the first sound given by either bird since his arrival). 
The fem;ile soon joined in, and a typical snake-ceremony followed. They 
then returned, the female leading, to the moss- bank. The male scrambled 
out again on to the bank, but at the other end from the nest. He trampled 
as before, but less often, and settled down, but did not pluck any moss. The 
female, however, after first pecking at the moss on the bank, turned, put 
her head under water, and proceeded to pull large pieces of moss up from 
the bottom. These she then jerked backwards over her shoulder, dropping 
them carelessly into the water and showing no further interest in them. 
This she did eiglit or nine times iu quick succession. After pecking up 
moss^ both birds usually gave a sharp, emphatic shake of the head. 
The male then got off, made for the shore near the true nest, and sat 
there some time on the mud. Then both came out onto open water, and 
a good deal of mewing in duet went on. 
The female then led the way to the moss-bank, where (I quote from my 
notes) "she beached herself, stern just in water, breast on land, head 
down. The male followed, mounted onto her, standing nearly upright, 
and copulated or attempted to copulate (it did not look as if he was 
