| OCR Text |
Show 330 ISLAND LIFE. [PAR'l' Il. 59. L. CALEDONIELL.A. North Britain (1854) . A local variety of the more widespread L. cO?·ylifoliella,. 60. L. DUNNlNGIELLA. North of England (1852). A somewhat doubtfnl species. 61. BuccuL.ATRIX DEMARYELL.A. Widely distributed (1848). Rather common. 62. TRIFURCUL.A SQU.AM.ATELL.A. South of England (1854). A doubtful species. 63. T . .ATRIFRONTELLA. South of England, also in Lancashire (1854). Very rare and peculiar. 64. NEPTICULA IONOBILIELLA. Widely scattered (1854). On hawthorn, not common. 65. N. POTERII. South of England (1858). Bred from Larvro in Poterium sanguis01·ba. 66. N. QUlNQUELL.A. South of Englnnd (18-1:8). On oak-leaves, very local. G7. N . .APICELLA. Locn1 (1854). Probably confused with allied species on the continent. · 68. N. HE.ADLEYELL.A. Local (1854). A rare specieR. PTEROPIJORIN .A. 69. AomsTrs BENNETTII. East coast (1840). Common on Statice lirnonium. We have here a list of sixty-nine species, which, according to the best authority, are, in the present state of our knowledge, peculiar to Britain. It is a curious fact that only five of these have been described less than twenty years ago; and as during all that time they have not been recognised on tho continent, notwithstanding that good coloured figures exist of almost all of them, it seems highly probable that many of them are really confined to our island. At the same time we must not apply this argument too rigidly, for the very day before my visit to Mr. Stainton he had received a letter from Professor Zeller announcing the discovery on the continent of a species of our last family, Pterophorina, which for more than forty years hacl been considered to be exclusively Hritish. This insect, Platyptilia similidactyla (Pterophonts isodactylus, Stainton's Manual), hacl been taken rarely in the extreme north and south of our islandsTeignmouth and Orkney, a fact which seemed somewhat indicative of its being a straggler. Again, seven of the species are unique, that is, have only been captured once ; and it may be supposed that, as they are so rare as to have been found only once in England, they may be all equally rare and not yet found on the continent. But this is hardly in accordance with the laws CHAP. X\'1.] THE DUITISU ISLES. 33l of distribution. Widely scattered species are generally abundant in some localities; while, when a species is on the point of extinction, it must for a time be very rare in the single locality where.it last maintains itself. It is then more probable that some of these unique species represent such as are almost extinct, than that they have a wide range and are equally rare everywhere; and the peculiarity of our insular climate, combined with our varied soil and vegetation, offer conditions which may favour the survival of some species with us after they have become extinct on the continent. In the list here given nine are recorded as varieties, whil ten more, in Mr. Stainton's opinion, onght probably to be classed as varieties or local forms of other species makinO' ' 0 nineteen in all. This leaves no less than fifty undoubted species not yet found beyond our islands; and though Mr. Stainton thinks that most of these will ultimately be found on the continent, we can hardly doubt, both from general considerations dependent on the laws of distribution, and from the peculiar habits, conspicuous appearance and restricted range of many of our species, that a very considerable number will remain permanently as peculiar British insects. Pec~tliarities of the Isle of Man Lepidopte1·a.-Before quitting the Lepidoptera, it will be well to notice some very interesting examples of local modification, apparently brought about by extreme conditions of exposure and insulation, and which throw some light on the way in which local forms, varieties, or species may be produced. This interesting phenomenon occnrs in the Isle of Man, where Mr. Edwin Birchall has collected Lepidoptera assiduously, and has discovered a number of varieties, apparently peculiar to the island, of which he has been so good as to send me specimens accompanied by some valuable notes. The Isle of Man has no woods, bogs, or heaths, the mountains being mostly covered with grass and rocks, so that a very abundant insect-fauna cannot be expected. Sixteen species of butterflies have been observed, and of these only one-the common tortoise-shell (Vanessa ~trticre) presents any peculiarity. This, however, iS' always remarkably small, a specimen rarely |
