It is well known that migrants under certain meteorological conditions travel at a great height, when it may fairly be presumed that the physical features of the earth's surface, the trend of mountain chains, or the course of great river systems, have little to do in determining their line, which is from point to point, and without deviation; yet in the vast majority of cases, where migration is visible, birds travel at a comparatively low altitude, so that when passing mountain chains, and even hills of no great altitude, they invariably choose the lines of the valleys, following depressions which, more or less, correspond to the general direction of their course. In the Cheviots I have observed, for two years in succession, that the streams of small migrants from Scotland follow those main valleys which run nearest north and south, sticking closely to the lowest levels, where the brushwood and bracken beds offer greater privacy and security than the bare fell sides. Birds also, when migrating, follow from choice low-lying tracks of land and river courses in preference to elevated plateau and the summit line of mountain ranges. Bearing these facts in mind, we find that there is a very well-marked line, both of entry and return, at the Farn Islands, on the coast of Northumberland. Scarcely second to this is the mouth of the Tees, both in spring and autumn. The North Yorkshire coast, from south of Redcar to Flamborough, including the north side of the headland, is comparatively barren, few birds appearing to come in between these points. Bridlington Bay and Holderness to Spurn and Lincolnshire, as far as Gibraltar Point, give perhaps the best returns of any on the East Coast. The north of Norfolk is poor, but there are indications in the heavy returns annually sent from the Llyn Wells, Dudgeon, Leman and Ower, and Happisburgh light-vessels, that a closely focused stream pours along the coast from E. to W., to pass inland by the estuary of the Wash and the river systems of the Nene and Welland into the centre of England, and thence probably following the line of the Avon, the north coast of the Severn, and Bristol Channel, and eventually striking across the Irish Sea, to enter Ireland near the Tuskar Rock, off the Wexford coast. This route is undoubtedly the great and main thoroughfare for birds in transit across England to Ireland in the autumn. Large numbers of migrants also which pass inland from the coasts of Holderness and Lincolnshire may eventually join in with the great western highway by the line of the Trent, avoiding altogether the mountainous districts of Wales. These remarks will refer chiefly to the Passerine birds, the _Accipitres_, _Limicolæ_, and _Gaviæ_, also Geese and Ducks, when crossing land, travelling as a rule very high.