35. Herring-Gull (Larus argentatus).—Breeding in considerable numbers at the foot of the mountain, on the shelving rocks over the sea. I think a few pairs breed in the breastwork of rock about the south point and the south-west side.
36. Great Black-backed Gull (L. marinus).—One pair had a nest and three eggs near the Herring-Gulls.
37. Razorbill (Alca torda).—I only saw two or three at the foot of the cliffs. They are said to breed in one inaccessible spot.
38. Guillemot (Uria troile).—About a score or more with the Razorbills. Probably the breeding-place is somewhere about the north-east corner. I do not think there can be many birds of either species there; for, although Razorbills began laying in another breeding-place in Lleyn at this date, no Guillemot's egg was seen until a day or two later, although the birds were sitting about the ledges. The proportion of Bardsey birds presumably on the cliff, and not seen by me, to those on the water would probably not have been large.
39. Manx Shearwater (Puffinus anglorum).—There is a considerable colony at the north-east end of the island, on the side of the mountain. When I left the breeding-place, about 9.30 p.m., all was quiet; but about midnight I could hear numbers crying incessantly "cock-cock-go-grow," or "cock-go-grow," over the fields in front of the house I was sleeping in. And one of my boatmen, who was coming along the road about that time, said that, although it was too dark to see them, they appeared to be flying about over the fields, low down. They breed chiefly on a steep grassy cliff varied by patches of fern, and large rocks which project from the turf. Some of the Shearwaters breed in holes under these rocks where they emerge from the turf; others in long clefts in, and winding passages among, the rocks. Most of the birds and eggs are quite inaccessible, but certain marks at the entrance denoted an occupied hole. Some of the birds were indignantly noisy when a stick was gently pushed into the easier holes. We extracted two birds and an egg from burrows. The birds are very savage, and bite everything within reach, and they inflict a painful bite. Another egg we could see in a cleft in the rocks, but could not reach. In one place there was a little cave under some rocks, and in it on the bare earth floor we could see an egg. The entrance of the cave was large enough, when a sod had been pulled away, for a young boatman to wriggle in on his stomach and fetch the egg; inside the cave was large enough for him to turn in. The bird must have retired to some inner fastness. Both the other eggs lay on the bare soil. As far as I have seen the ground immediately in front of holes selected by Shearwaters to breed in always falls very sharply; indeed, in some
