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THE PLEISTOCENE SITE OF IPSWICH.
street-diggings are made, and sometimes fossils of those old Glacial days have been unearthed in even Westgate and Carr streets. I t is not, perhaps, too m u c h to suggest that the presence of this terrace, high above even the winter floods and yet within convenient reach of the river, was a main reason why our earlyhistoric people began to erect a town upon the spot. T h e wide piain, traversed by good water and well sheltered northerly, constitutes an ideal home : its soil was dry and well open to the south, the basic water-supply was ample and access to the sea free, though sufficiently distant for protection from piratical rovers. River Orwell must be thanked for all these benefits as, through countless ages, it has cut its course adown t h e Valley and, in the later stages of so gigantic a task, washed out the broad terrace that is the town's backbone to-day.
ON PLUMAGE OF THE BY CHESTER G .
DOUGHTY,
GANNET. B.A.
THE fresblv disembodied skin of a Gannet (Sula bassana, L.) without head or legs, with only half a wing but a complete white tail, showing it to be a mature bird, was discovered on t h e shore at Gorleston on 8 December 1932, though not much of a prize to the hardened old beach-combing Naturalist. But later I found the other half of the wing about fifty yards away and, noticing its white primary ; saw it must be taken home for further investigation. A few days afterwards I came upon the other wing some quarter-mile f r o m the original d e b r i s : and thus assembled very useful material, exhibiting three peculiarities in the plumage : (i) It does not moult its feathers in pairs, i.e. the corresponding feathers on the two sides of the body ; (ii) T h e new feathers of a pair, when produced, do not always agree with each other in markings and c o l o u r ; and (iii) It has a distinct tendency to produce white feathers, where they should be dark. Attention ought to be called to these facts, because most ornithologists have few or no opportunities of handling Gannets in t h e flesh. I must point out that the juvenile is an entirely dark bird specklcd with w h i t e ; and that the mature one, after numerous moults, is an entirely white bird with the exception of its ten long primaries, which are very dark brown, and of its head and neck, which are pale b u f f : these remarks apply to the plumage only and not the soft parts. T h e effect of (i) therefore is sometimes rather curious. It appears that an old all-dark secondary quill may be replaced by a new all-white quill at a Single moult, and consequently a new white secondary in one wing may be paired by an old dark secondary in the other ; and, when it is