The first list of mollusca from the Pleistocene deposits at Barrington was published by Mrs. T. McKenny Hughes in 1888 and enumerated twenty-four species. In 1911 Prof. T. McKenny Hughes recorded twenty-seven species, and added some details regarding one of the species. In 1918 one of us (B. B. W.) mentioned six species of Pisidium , five of which were new records. Several visits have been made to this deposit, and a large amount of material has been washed, the conditions existing at the pit greatly facilitating this work. We are, therefore, now able to register fifty-four species, as follows:— Limax maximus Linné. Five examples. L. arborum Bouchard-Chantereaux. Abundant. Agriolimax agrestis (Linné). Common. Milax gagates (Draparnaud). One example. Polita nitidula (Draparnaud). One example. P. pura (Alder). Two examples. P. radiatula (Alder). Two examples. Zonitoides nitidus (Müller). One example. Euconulus fulvus (Müller). Common. Arion sp. One granule. Punctum pygmæum (Draparnaud). Abundant. Pyramidula rotundata (Müller). Two examples. Helicella virgata (DaCosta). Common. H. itala (Linné). Common. Hygromia hispida (Linné). Abundant. Acanthinula aculeata (Müller). Three examples. Vallonia pulchella (Müller). Common. V. excentrica Sterki. Common. V. costata (Müller). Common. Helicodonta obvoluta (Müller). Two Helix nemoralis Linné (fragments). Common.