Recently, I wrote (Moore, 1978) that no substantiated records existed for Corophium sextonae Crawford amend. Hurley (Amphipoda) north of Abereiddy Quarry, S. Wales. The records of the species for the West coast of Scotland given by Scarratt (1961, Ph.D. Thesis, University of Wales) have been regarded as suspect on the basis of wrongly labelled material from his type collection now (with his kind permission) in my possession. My own investigation of amphipods from kelp holdfasts in the Clyde Sea area and its environs, over many years have failed to produce this species.

C. sextonae has now, however, been identified with certainty from a collection (made on 6 September 1979) of Ascidia mentula Muller taken from a rope suspended (on 26 April 1979) from the U.M.B.S. raft in Linne Mhuirich, a marine lake off Loch Sween, lat. 55° 59′ N, long 5° 39′ W, O.S. ref. NR732853. Both male and ovigerous female C. sextonae were included in the material. They were living in silty tubes attached to the tests of the ascidians, together with Jassa falcata (Montagu) and Microdeutopus anomalus (Rathke).

Personal collections of kelp holdfasts and other algae (Codium, ‘red algal turf’ mostly Bonnemaisonia) in the nearby rapids (ca. 3·2 km distant) at Linne Mhuirich in May 1969 (Moore, 1971, Ph.D. Thesis, University of Leeds) and in June 1974 (Shillaker & Moore, 1978) failed to disclose any C. sextonae (all Corophium were C. bonnellii). C. sextonae may be very localized within Linne Mhuirich, given Moore's (1978) observations on Lundy; the acknowledged unique hydrography of Linne Mhuirich (Kerr, 1912; Lewis & Powell, i960) and the sensitivity of the species to water movement gradients (Hughes, 1975).