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Show 320 ISLAND LIFE. [PART H. Plants, which have considerable facilities for passing over the sea, are somewhat intermediate in proportionate numbers, there being about 070..fiowering plants and ferns in Ireland to 1425 iu Great Britain,-or almost exactly two-thirds, a proportion intermediate between that presented by the birds and the mammalia. Peculiar British Birds.-Among our native mammalia, reptiles, and amphibia, it is the opinion of the best authorities that we possess neither a distinct species nor distinguishable variety. In ?irds, ~owever, the case is different, since some of our species, In particular our coal-tit (Parus ater) and long-tailed tit (Parus caudatus) present well-marked differences of colour as compared with continental specimens; and in Mr. Dresser's work on the Birds of E1trope they are considered to be distinct species, while Professor Newton, in his new edition of Y arrell' s British BiTds does not consider the difference to be sufficiently great or suffi~ ciently constant to warrant this, and therefore classes them as insular races of the continental species. We have, however, one undoubted case of a bird peculiar to the British Isles, in the red grouse (Lagopus scoticus), which abounds in Scotland Ireland t l1 e ~ orth of E~gland, and Wales, and is very distinct f' rom any' contmen~al s~ee1es, ~lthough closely allied to the willow grouse ?f Scandmavia. This latter species resembles it conside.rably in Its summer plumage, but becomes pure white in winter· whereas . . . ' our .species retams Its dark plumage throughout the year, be-commg even darker in winter than in summer. We have here therefore a most interesting example of an insular form in our own country; but it is difficult to determine how it originated. On the one hand, it may be an old continental species which during the glacial epoch found a refu<re here when driven from • • b Its native haunts by the advancing ice; or, on the other hand, it may .be a descendant of the Northern willow grouse, which has lost Its power of turning white in winter owincr to its lon<r residence in the lowlands of an island where there is 0 little perm:nent snow, and where assimilation in colour to the heather amoncr which it lurks is at all times its best protection. In either cas~ it is equally interesting, as the one large and handsome bird which is peculiar to our islands notwithstandino- their recent separation from the continent. 0 CHAP. XVI.] THE BRITISH ISLES. 321 The following is a list of the birds now held to be peculiar to the British Isles:- l. PAR US BRITANNICUS ... Closely allied to P. ate1· of the continent ; a local race or sub-species. 2. PARUS ROSEA ............ Allied toP. caudat·us of the continent. 3. LAGOPUS scOTicus ...... Allied to L. albus of Scandinavia, but very distinct. F1·eshwate1' .Fishes.-Although the productions of fresh waters have generally, as Mr. Darwin has shown, a wide range, fishes appear to form an exception, many of them being extremely limited in distribution. Some are confined to particular river valleys or even to single rivers, others inhabit the lakes of a limited district only, while some are confined to single lakes, often of small area, and these latter offer examples of the most restricted distribution of any organisms whatever. Cases of this kind are found in our own islands, and deserve our especial attention. It has long been known that some of our lakes possessed peculiar species of trout and charr, but how far these were unknown on tbe continent, and bow many of those jn different parts of our islands were really distinct, had not been ascertained till Dr. Gunther, so well known for his extensive know ledge of the species of fishes, obtained numerous specimens from every part of the country, and by comparison with all known continental species determined their specific differences. The striking and unexpected result has thus been attained, that no less than fifteen well-marked species of freshwater fishes are altogether peculiar to the British Islands. The following is the list, with their English names and localities :- 1 F1·eshwater Fishes peculiar to the British Isles. Latin Name. 1. SALMO BRACHYPOMA .. 2. , GALLI\"ENSIS .. 3. , ORCADENSIS .. . 4. 11 FEROX ....... .. . English Name. Short·headed salmon Galway sea-trout .... Loch Stennis trout .. Great lake-trout ...... Locality. Firth of Forth, Tweed, Ouse. Galway, y.,r est Ireland. Lakes of Orkney. Larger lakes of Scot-land, theN. of England, and Wales. t The list of names was furnished to me by Dr. Gunther, and I have added the loealities from the papers containing the original descriptions, and from Dr. Haughton's B1·itish F1·eshwate1· Fishes. y |