201 JUNCUS TENUIS Willd. IN NORTH WALES. By J. Lloyd Williams. Mr. Arthur Bennett {Journ. Bot. 1895, 39) raises the interesting question whether Juncus tenuis is a recent introduction. He draws attention to the British and foreign records given, and the plants said to be associated with it, and invites further details respecting these points. A fuller description of the Portmadoc locality, where the plant was found by the Eev. W. H. Painter and the writer (Journ. Bot. 1891, 120), and of two new localities in the same district, may assist in throwing light on this question. The Traetli Mawr is a flat valley extending inland for about six miles. The river forming the boundary between Carnarvon and Merioneth runs through it. As late as the close of last century it was partly covered by the sea. Asplenium marinum grows even now on some rocks at the very head of the valley above the road from Beddgelert to Tanybwlch, while Armeria vulgaris^ Silene niaritima, Asplenium lanceolatum, and other littoral plants are found in various places round the valley and on the islet-like rocks rising out of it. All this shows that at a comparatively recent period the whole valley must have been a land-locked bay. About the beginning of the century the Portmadoc embankment was built and the land reclaimed, with the exception of a small portion just within the embankment, which is always covered by a varying amount of brackish water. Near this, such plants as Carex (Ederi, C. extensa, Triglochin, &c., grow, while the remainder of the land as far as the railway running parallel with the embankment is almost entirely occupied by a very rough pasture full of gorse and tufts of Juncus communis, J. maritimus, &c. The soil is sandy, but not marshy. Juncus tenuis is confined to the cattle tracks which intersect this portion, and it extends along several of them for twenty or forty yards. I failed to find it in the wetter parts near the water or in the better land on the other side of the railway. On subsequent visits with botanical friends, we had some difiiculty in finding the plant again. The part where it used to flourish best had been railed- off from the cattle, the tracks had become overgrown with herbage, and the Juncus had nearly all disappeared. We, however, found it growing plentifully in the new tracks which had been made by the cattle. Last summer, as Mr. D. A. Jones, of Harlech, and I were crossing the Traeth along a grassy footpath opposite the village of Prenteg, about two miles further inland than the above locality, we came upon a fairly large number of fine tufts of the rush. It is a noteworthy fact that the only portion of the footpath occupied by the plant was a part along which cattle were in the habit of passing to and from a farmyard. Here again we were on reclaimed land, and the soil was sandy and not wet. Soon after this, Mr. Jones sent me specimens from above Harlech, in the county of Merioneth, a few miles to the S.E. of Portmadoc. The following is his de- scription of the locality : — *' The plant grew about 2^ miles above
