the young fully attained their adult plumage and are capable of sustained flight. Then the whole great host takes wing into the unknown, literally so; for, so far as I can learn, this species, Diomedea immutabilis Roth, absolutely disappears from human ken for about two months of each year. There seems to be some evidence that it betakes itself to the Arctic seas. The apparent obliteration of this 
Fig. 11. Hovering with Graceful Poise like Immense White Butterflies. vast swarm of birds for a definite period annually is a mystery still to be solved. In November the birds arrive at Laysan as suddenly as they departed, and at once begin to prepare for domestic responsibilities. During the ten months annually spent there they do not appear to wander far from their breeding grounds. Indeed our vessel did not encounter them so far to the eastward as the main Hawaiian group.
Great as is the multitude of albatrosses and conspicuous as they are on account of their size, the terns of five or six species greatly exceed them in number, probably forming more than half of the entire bird population of the island. The clamor that greets the intruder in one of these immense tern rookeries is simply appalling, the air fairly quivering with their ear-splitting shrieks as they circle in clouds around his head and dash savagely directly at his face in their fierce endeavor to drive him away. There were probably hundreds of bushels of eggs of these birds 
Fig. 12. Rookery of 'Love Birds.' at the time of our visit. The most numerous terns are the 'black-backed' and 'gray-backed' wideawakes, of which there must be millions, nesting among the bushes and tufts of grass, particularly on the southern end of the island. The vegetation grows right in the dazzling white coral sand, which appears as white as snow in the photographs.
One of the most exquisitely beautiful birds that the writer has ever seen is a small tern known locally as the 'love bird,' pure white with large black eyes and bill. They have the habit of hovering with graceful poise over the intruder, like immense white butterflies, silently inspecting one as if impelled by a mild curiosity rather than resent-
