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No Binding. Zustand: Very Good. ORIGINAL1948 reprint/offprint of journal article; no covers issued; light browning of leaves; o/w in very good condition. Journal.

1. The bed of the Lough Ine Rapids is covered by large laminarian seaweeds, mainly Saccorhiza bulbosa. The fronds form a dense canopy, which has a typical fauna associated with it. 2. A study has been made of the speed of the water current at the level of the canopy throughout the tidal cycle (12 1/2 hr.) at a series of selected stations. The total lengths of water-columns passing and the maximal speed of the current at each station are given in Table 1. The various stations range, in maximal speed of current, from a very low value up to 2 1/2 m./sec. 3. An investigation has been made of the distribution of animals associated with the canopy. This investigation comprises both general observations made throughout the Rapids area and a detailed study of samples of Saccorhiza collected at the stations mentioned above. Of the animals studied six species (three polyzoans and three gastropods) were confined to situations where they were exposed to weak currents only, that is, on the fronds of Saccorhiza at stations of quiet water and in some cases in the shelter of the crenulated margins (`frills') of the stipes at stations of stronger current. Two species (the polyzoan Membranipora membranacea and the limpet Patina pellucida) favoured moderate current and were less abundant in weak or strong current. Two species (the amphipod Jassa falcata and the hydroid Tubularia bellis) favoured proximity to strong current but not direct exposure to it. 4. In experiments with the gastropod Gibbula cineraria it was shown that the adult animal was washed off Saccorhiza by strong currents. 5. There are many ways in which current may directly or indirectly influence the distribution of animals in an area such as the Lough Ine Rapids. Moreover, it may act differently at different stages of the life histories of these animals. Although current is no doubt of paramount importance in the Lough Ine Rapids, the interpretation of the complex interaction of its many effects upon the animals must await much more experimental evidence and must be approached with great caution. 22 pp., 14 figs, gr. 8.