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Show 326 ISLAND LIFE. (PART H. recorded peculiarities in the insect world, for it is ?nly by so doing that we can hope to arrive at any correct solutiOn ~f .the question on which there is at present so much difference of opmwn. For the list of Coleoptera with the accompanying notes I am indebted to Mr. E. C. Rye; and Dr. Sharp has also given me valuable information as to the recent occurrence of some of the supposed peculiar species on the continent. For the Lepidoptera I first noted all the species and varieties marked as British only in Staudinger's Catalogue of European Lepidoptera. This list wa.s carefully corrected by Mr. Stainton, who weeded out all the species known by him to have been since discovered, and furnished me with valuable information on the distribution a.nd habits of the species. This information often has a direct bearing on the probability of the insect being peculiar to Britain, and in some cases may be said to explain why it should be so. For example, the larvre of some of our peculiar species of Tineina feed during the winter, which they are enabled to do owing to our mild and insular climate, but which the severer continental winters render impossible. A curious example of the effect this habit may have on distribution is afforded by one of our commonest British species, Elachista rufocine?·ea, the larva of which mines in the leaves of Holc~ts mollis and other grasses from December to March. This species, though common everywhere with us, extending to Scotland and Ireland, is quite unknown in similar latitudes on the continent, but appears a.gain in Italy, the South of France, and Dalmatia, where the milJ winters enable it to live in its accustomed manner. Such cases as this afford an excellent illustration of those changes of distribution, dependent probably on recent changes of climate, which may have led to the restriction of certain species to our islands. For should any change of climate lead to the extinction of the species in South Europe, where it is far less abundant than with us, we should have a, common and wide-spread species entirely restricted to our islands. Other species feed in the larva state on our common gorse, a plant found only in limited portions of Western and Southern Europe ; and. the presence of this plant in a mild and insular climate such as ours may well be supposed to have led to the CHAP. XH] 'rilE BHlTISH H\LI~S. 327 preservation of some of the numerous species which arc or have been dependent on it. Mr. McLachlan has kindly furnished me with some valuable information on certain species of Trichoptera or Caddis Hies which seem to be peculiar to our islands; and this completes the list of orders which have been studied with sufficient care to a-fford materials for such a comparison. We will now give the list of peculiar British Insects, beginning with the Lepidoptera, and adJing such notes as have been kindly supplied by tltc gentlemen already referred to. List of the Species or Vatielies of Lepidopte1·a which, so fw· a.~ ctl p1·esPnl lr·nown, ewe confined to the B1·itish Islands. ('l'hejigu1·es show the datrs when the species was ji1·st described.) DrurtNr. I. PoLYOMMA'rus DISPAR. "The large copper." This fine insect, once common in the fens, but now extinct owing to extensive drainage, is generally admitted to be pec.uliar to onr island, at all events as a variety or local form. Its continental ~~lly differs constantly in being smaller and in having smaller spots ; but the difference, though constant, is so slight that it is now classed as a variety under the name of ?'utilus. Our insect may therefore be stated to be a well-marked local form of a continental species. 2. Lycren:t astrarche, vm·. ARTAXERXE8. This very distinct form is confined to Scotland and the north of England. The species of which it is considered a variety (more generally known to English entomologists asP. agestis) is found in the southern half of Enghnd, and almost everywhere on the continent. BoMnYcEs. 3. LITHOSI.A. SEIUCEA. North of England (1861). 4. Hepialus humuli, ?;w·. IIETIILANDICA. Shetland Islands (18G.J). A remarkable form, in which the male is usually yellow and buff instead of pure white, as in the common form, but exceedingly v:1riable in tint and markings. 5. EPICIINOPTERYX RETICI'~LLA. Sheerness, Gravesend, nnJ other localities along the Thames (1847). G. E. pulla, var. RADIEI.LA. Near London, rare (1830 ?) ; the species in Central and Southern Europe. (Doubtfully peculiar in Mr. Stainton'::J opinion.) NocTU.lF,. 7. AcRONYCTA MYRIClE. Scotland only (1852). A distinct species. 8. AartOTIS SUBROSEA. Cambridgeshire and Huntingdonshire fens, perhaps extinct (1835). Tho vm·. subcce?"tclea is found in Finla.nd and Livonit~. |