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Show 1868.] MR. R. B. SHARPE ON THE GENUS CEYX. 587 which have two spines on the anterior rim of the thorax, are marine, while those of the genus Palcemon, with the two spines of the thorax placed one behind the other, are exclusively freshwater forms. This is decidedly wrong, according to m y own observations in the Philippines. There are genuine species of Palcemon and Leander in the sea as well as in rivers and lakes. Philippi's genus Bithynis, with only one spine on the anterior rim, may therefore be considered a third subgenus of Palcemon. The synonymy of this species is therefore as follows : - Palcemon gaudichaudii, Olivier. Palcemon ceementarius, Poeppig. Bithynis longimana, Philippi. Macrobrachium africanum, Spence Bate. I am very glad that I need not change the latter name, which I should be obliged to do if it really were a new species. Mr. Spence Bate seems to be of opinion that the Tambo River is in Africa, whereas it is really on the west coast of South America, near Islay in Peru. The original specimens were collected there by Mr. Whitely. When Mr. Spence Bate expresses the opinion that all the four species of his supposed new genus have descended from one single primitive form, the reasons which he alleges in favour of this view are not convincing. My own observations in the Philippines make me rather doubtful of the alleged fact that only one particular and no other Palsemonide inhabits each river and lake. The new genus of Mr. Spence Bate must therefore be suppressed, and also three of his supposed new species. It is not a new fact that these large species of Palcemon can be eaten, nor that they live in fresh water. The older naturalists, as Sloane, Parra, Leach, Poeppig, and Philippi, knew it long ago, as may be seen from their writings. 7. On the Genus Ceyx. By R. B. SHARPE. It seems necessary to say a few words on this genus, as considerable confusion still exists with regard to the correct determination of some of the species ; and I am further anxious to set right a point in the synonymy of two of them, by which I myself, in m y ' Monograph of the Al'cedinidee,' as well as other ornithologists, have been led into error. The genus Ceyx was established in 1801, by Lacepede, and the species included in it have only three toes. The birds seem principally insectivorous, in contrast to the members of the three-toed genus Alcyone, the species of which are closely allied to true Alcedo, and are almost wholly piscivorous. All the members of the genus Ceyx seem occasionally to feed on fish, but are not generally found in the neighbourhood of streams. In their general habits they are allied to the African Lspidinee. The genus Ceyx may be divided into two natural sections, viz. |