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Show 33S 1SLAND LIFR. (PAHT II. peculiarity of the soil alHl water in ihe former i~;lam1, ha~·~ really led to the prod uetion or preservation of a well-marked. variety of msect. Land and Fresh-water Shells.-As regards the land and fresh-water mollusca it seems difficult to obtain accurate information. Several species have been recorded as British only • but I am informed by Mr. Gwyn Jeffries that most of tl:es.e are decidedly continental, while a few may be classed as vanetws of continental species. According to the late Mr. Lovell Reeve the following species are peculiar to our islands ; and altho":gh the first two seem extremely doubtful, yet the htst two, to whlCh alone we accord the dignity of capital type, may not improbably be peculiar to Ireland, being only found in the remote southwestern mountain region, where the climate possesses in the hi()·hest derrree the insular characteristics of a mild and uniform 0 b temperature with almost perpetual moisture, and whore seveml of the peculiar Irish plants alone occur. 1. Cyclas pisidioides.-A small bivalve F~hell found in canals. .Perl1apR a variety o.f C. comeum or C. 1·ivicola according to Mr Gwyn J e:ITnes. 2. Assiminia grayana.-A small univalve shell allied to the pcriwinklcR, found on the banks of ihe Thames between Greenwich and Gravesend, on the mud at the roots of aquatic plants. 3. G JJ:Q;\fAI,ACUS MACULOSUS.-A beautiful slug, black, spotted with yellow or white. It is found on rocks on the shores of Lako Ct;,rogll, south o[ Castlemain Bay, in Kerry. It was discovered in 1842, and has never been foand in any other locality. An allied species is found in Portugal anu France, which Mr. Gwyn Je.firies thinks may be identical. 4. LIMNJEA INVOLU'l'A.-A beautiful pond-snail with a small polished umber-coloured shell, found only in a small alpine lake and its inflowi11g stream on Cromaghaun mountain near the lakes of Killarney. It appears to be a very distinct species, most nearly allied to L. glutinosa which iR not found in Ireland. It was discovered in 1832, and has frequently been obtained since in the same locality. The facts-that these two last-named species have been known for about forty or fifty years respectively, that they have never been found in any other locality than the above named very restricted stations, and that they have not yet been clearly identified with any continental species, all point to the conclusion that they are the last remains of peculiar forms which have everywhere else become extinct. Pec~tlirwities of the Brit?'sh Fl01·a.-Thinking it probable CllAP. XV1.) TITE DRITISII ISLES. 339 that th~re must also be some peculiar British plants, but not findmg any euumeration of such in the B1·itish FloretS of Babin~ton, Hooker, ~r ~entham, I applied to the greatest living au_thonty on the distnbution of British plants-Mr. H. C. Watson, who has very kindly given me all the information I required, and I cannot do better than quote his words. He says : "It may be stated pretty confidently that there is no 'spec~es' (generally. ~ccepted among botanists as a good species) peculiar to the Bntish Isles. True, during the past hundred years, nominally new species have been named and described on British specimens only, from time to time. But these have gradually come to be identified with species described elsewhere und~r other n~mes-or they have been reduced in rank by succeedmg botamsts, and placed or replaced as varieties of more widely distributed species. In his British Rubi Professor Babington includes as good species, some half-dozen which he has, apparently, not identified with any foreign species or variety. None of these are accepted as ' true species,' nor even as ' subspecies' in the Students' Fl01·a, where the brambles are descri?e~ by Baker, a botanist well acquainted with the plants of Bntam. And as all these nominal species of -Rubi are of late creation, they have truly never been subjected to real or critical tests as ' species.' " But besides these obscure forms, about which there is so much difference. of opinion. a~ong botanists, there are a few flowering plants ~hwh, as vanetMs or sub-species, are apparently peculiar to our Islands. These are :-(1) Helianthemum BreweT{ an annual rock-rose found only in Anglesea .and Holyhead Island (c~assed as a sub-species of I£. gutt(lt~tm by Hooker an~ ~abmgton); (2) Rosa hibernica, found only in North Br~t~m and Irelan~ (a species long thought peculiar to the Bnt1sh Isles, but s.al~ ~o have been recently found in France); (3) CEnanthe jluv~at~lis, a water-dropwort, found only in the south of E~gland and in one locality in Ireland (classed as a sub-species of CE. phellandrium by Hooker); (4) Hieracium i1·i?um, a hawk-weed found .in North Britain and Ireland (classed by Hooker as a sub-species of H. Lawsoni, aml said to be " confined to Great Britain)." z 2 |
