The single white egg is deposited during the latter half of June down holes in heaps of stones, in rabbit-burrows, or in any other spot affording suitable concealment. Incubation, which is probably undertaken by both sexes, lasts about thirty-five days, the nestling when hatched being covered with long black down. Their food consists of crustaceans, small fish, and fatty matter of any kind. They are nocturnal, during the breeding season at all events, only leaving their retreat after dark and returning before dawn, so that it is very difficult to detect their presence. The sitting bird, however, utters a curious note while sitting, and a strong musky odour pervades the burrow, so that by this means the nest may frequently be found. If handled, the bird emits a greenish oil. In England it only nests sparingly on the coast of Wales and in the Scilly Islands, but in Scotland and Ireland its breeding places are numerous. The adult is sooty black all over, but the bases of the tail coverts are white and the edges of the wing coverts are slightly edged with white. Length 6·5 in.; wing 4·7 in. LEACH’S FORK-TAILED PETREL Oceanodroma leucorrhoa (Vieillot) This species is a regular but not very numerous visitor to our shores every autumn, its numbers depending largely on the weather, and after heavy gales it is often found inland. It nests in small numbers on St. Kilda and some of the Outer Hebrides, and has also been found nesting off the coast of Kerry; and in time many other breeding stations will probably be found on the islands of our western shores. The single egg is white freckled with rusty spots. In its food and habits it resembles, so far as they are known, those of the Storm Petrel. The adult is dark leaden black, rather more sooty below; upper tail coverts white; tail sooty black and deeply forked. Length 8 in.; wing 6 in. [Illustration: STORM PETREL _Procellaria pelagica_ (right) LEACH’S PETREL _Oceanodromas leucorrhoa_ (left)] MADEIRAN FORK-TAILED PETREL Oceanodroma castro (Harcourt) An example of this bird was picked up dead in Kent in December 1895. The home of this species is the islands lying off the west of Africa, viz. Cape Verde, Madeira, Desertas, Salvages, and Canaries, from whence individuals occasionally wander to Europe. This species very closely resembles Leach’s Petrel, but the tail is hardly forked; the upper tail coverts are white tipped with black; and the bases of the tail feathers are white. Length nearly 8 in.; wing 5·9 in. WILSON’S PETREL Oceanites oceanicus (Kuhl)