IN THE SHETLANDS E27 
bird itself, when seen in the opposite sex. Why, 
then, should the pale mauve or blue of the inside of 
the mouth—this purple chamber flung open for in- 
spection during the season of courtship or of nuptial 
dalliance—be not appreciated too? 
The razorbill’s mouth, inside, is of a conspicuous 
light yellow, which, when exposed suddenly to 
view, contrasts very forcibly with the black of the 
beak and upper plumage. In dalliance these birds 
throw the head straight up into the air, and, opening 
their clean-cut bills, so that one sees the gay in- 
terior like a line of bright gamboge, utter a deep 
guttural note, which is prolonged and has a vibratory 
roll in it, like the cry of the gorilla when angry 
— si parva licet componere magnis—as described by 
Du Chaillu. It is not loud, however, and so is easily 
lost amidst elemental sounds and the cries of other 
birds. The vibratory character of the note becomes 
more marked under the influence of excitement, and 
the mandibles themselves vibrate as they are opened 
at intervals, somewhat widely. In the midst of their 
duet the pair toss their heads about, catch hold of 
each other’s beaks, and give quick little emotional 
nibbles at the feathers of their throats or breasts. If 
we can suppose that the birds are interested in each 
other’s appearance whilst thus acting—that they ad- 
mire or are sexually excited by one another—then it 
would be strange if the bright flashing yellow so con- 
stantly exhibited did not play its full part in producing 
this result. Imagine ourselves razorbills, and thus 
