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BOTANY duced into Berks, Middlesex and Bucks, and are now a conspicuous feature in the clover and corn fields, and by the roads and railways, their feathered fruits being carried by the wind over ever-widening areas, and thus yearly make a westerly advance into fresh country. The hoary cress first appeared in our county on the rubbish heaps at the sewage works. At that time some portion of the dried refuse was sold for manure, and in this way the cress has been carried to widely separated stations. The plant is supposed to have been introduced to Britain with the fodder brought by the vessels which conveyed the un- fortunate Walcheren expedition, and is now a pest to the agriculturist in the Isle of Thanet. A semi-maritime species of grass, Glyceria or Pani- cularia distans, was also very common about the sewage works in 1879, but I cannot learn that it has spread to other situations. The washing of skins in our streams by fellmongers, etc., has led to the introduction of several foreign species. The seeds which had become entangled in the wool of foreign animals, in the washing have been separated and sunk into the mud. When the river Nene was dredged, the surface of the mud scattered on the adjoining meadow showed several foreign species which flourished for a season or so, but partly from the cold season, and I think chiefly from the stress of the keen competition for the soil by the strong native species of grass, these outlanders soon disappeared. About our corn mills a few foreign casuals may be seen : these include Couringia orientalis, Plantago arenaria, Santia {Polypogon) monspeliensis. Another factor in the introduction of foreign casuals must receive brief notice, as it is quite conceivable that some of the plants thus introduced may become permanent features in our flora. I refer to our railways. At the present time no inconsiderable acreage of North- amptonshire is taken up with the sidings, embankments, and cuttings of the various railway systems which traverse the county. The railway banks often give one a better idea of the native flora than the surround- ing ground which is under cultivation, as our competing grasses and other strong species have not had time to exert their overcrowding pro- perties, while the drainage and the sunny exposure often give plants which are fond of an open situation facilities which the more uniform, sheltered, shaded, and highly cultivated arable or pasture country no longer affords ; hence we see the hare's-foot clover [Trifolium arvense), the mouse-ear hawkweed [Hieracium Pilosella), the field scorpion grass {Myosotis versicolor), doing extremely well on railway banks. Moreover when a cutting has been made through clay, the moist surface acts as a sticky fly-paper does, and light seeds which are borne by the wind become attached, and in a short time the clay is covered with vegetation which is in many instances foreign to the district round. These clay cuttings afford us the bee orchis {Ophrys apifera), the melilot [Melilotus officinalis), the rose bay willow herb [Epilobium angustifolium) , and the Crepis taraxacifolia already referred to, while the abundance of coltsfoot and thistles show what an advantage the feathery pappus-borne fruits have over the more heavy ones which are dependent upon other means 55