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Show 1878.] AND DISTRIBUTION OF THE CRAYFISHES. 753 species of freshwater Astacidee and the marine genus Nephrops;" and " as the species referred to Paranephrops differed less from [some of] those of Astacoides than these latter did from one another, and as, moreover, the latter name had the priority, he proposed provisionally to refer the New-Zealand species oi Astacidee to it." Mr. "Wood-Mason is unquestionably right both in denying any special relationship between Paranephrops and Nephrops, and in asserting that the New-Zealand Crayfish differ less from some of the species of the genus Astacoides, as its limits are at present understood, than these do from one another. But I shall have occasion to show that the type of the genus Astacoides, the Madagascar Crayfish, differs so widely from the other Crayfishes of the southern hemisphere, that the latter cannot be included in the same genus ; while Paranephrops is sufficiently different from the Australian and Tasmanian Crayfishes to render its recognition as a distinct generic type desirable *. The distribution of the Crayfishes, so far as it is hitherto ascertained, is not a little remarkable. Astacus fluviatilis occurs in various parts of England and in Ireland; but I cannot find any record of it in Scotland. Dr. M'Intosh, who has been kind enough to look into this point in aid of m y inquiries, assures m e that Crayfishes are not indigenous to that part of Britain, that they do not exist in the Tweed and the Teviot, and that an attempt to introduce them into the island of Mull failed ; they were placed in various streams, but none were ever seen again. Even in England, Crayfishes appear to be restricted to certain rivers. They abound, for example, in the Thames; but I cannot hear of any in the Cam or the Ouse, though their absence in the latter rivers cannot be ascribed to any want of calcareous matter in the districts through which those rivers flow. Astacus jiuviatilis, however, extends all over the western half of Europe, as far south as the Pyrenees and the northern shores of the Mediterranean; while, eastward, it reaches Sicily, Northern Greece, and the western shores of the Black Sea. In Spain there appears to be no doubt that it occurs about Barcelona; but whether it is found in the rest of the Spanish peninsula is uncertain -*. Northwards and eastwards, Astacus jiuviatilis extends to Sweden and the Baltic provinces of Russia, and through Western Russia, by the basins of the Dniester and the Bug, to the Black Sea. Over this vast area, marked local varieties appear to be not uncommon ; and most authors agree to regard a Crayfish which occurs in Southern Europe, France, Switzerland, and Germany, and which 1 See on this subject the remarks of Mr. Miers, " Note on the genera Astacoides and Paranephrops" (Ann. & Mag. Nat. Hist. ser. 4, vol. xviii. 1876). 2 See Gerstfeldt, " Ueber die Flusskrebse Europa's " (Mem. presented a l'Acad. Imp. des Sciences de St. Petersbourg, 1859, p. 587). As far back as 1675, Sachs a Lewenbeimb wrote:-"Sic in Hispania licet flumina, negant inveniri ibi Cancros fluviatiles, coutra in Gallia frequentissimi, item in Pannonia, in Helvetia, in Germania; etiam in fluviis Americanis inveniri referunt navigatores. In fluvio Lydia? Haly cancros invenit Busbequius, Ep. Turc. i. p. 89.'' But were these Lydian " cancri" crayfishes or fluviatile crabs ? |