338 



ISLAND LIFE. 



[part II. 



peculiarity of the soil and water in the former island, have really led to 

 the production or preservation of a well-marked -variety of insect. 



Land and Fresh-iuater Shells. — As regards the land and 

 fresh-water mollusca it seems difficult to obtain accurate infor- 

 mation. Several species have been recorded as British only, 

 but I am informed by Mr. Gwyn Jeffries that most of these are 

 decidedly continental, while a few may be classed as varieties of 

 continental species. According to the late Mr. Lovell Reeve 

 the following species are peculiar to our islands ; and although 

 the first two seem extremely doubtful, yet the last two, to which 

 alone we accord the dignity of capital type, may not improbably 

 be peculiar to Ireland, being only found in the remote south- 

 western mountain region, where the climate possesses in the 

 highest degree the insular characteristics of a mild and uniform 

 temperature with almost perpetual moisture, and where several 

 of the peculiar Irish plants alone occur. 



1. Cyclas pisidioides. — A small bivalve shell found in canals. Perhaps 

 a variety of C. corneum or C. rwicola according to Mr Gwyn Jeffries. 



2. Assiminia grayana. — A small univalve shell allied to the periwinkles, 

 found on the banks of the Thames between Greenwich and Gravesend, on 

 the mud at the roots of aquatic plants. 



3. Geomalacus maculosus. — A beautiful slug, black, spotted with yellow 

 or white. It is found on rocks on the shores of Lake Carogh, south of 

 Castlemain Bay, in Kerry. It was discovered in 1842, and has never been 

 found in any other locality. An allied species is found in Portugal and 

 France, which Mr. Gwyn Jeffries thinks may be identical. 



4. LiMN^A INVOLUTA.— A beautiful pond-snail with a small polished 

 amber-coloured shell, found only in a small alpine lake and its inflowing- 

 stream on Cromaghaun mountain near the lakes of Killarney. It appears 

 to be a very distinct species, most nearly allied to L. glutinosa which is 

 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 iden- 

 tified with any continental species, all point to the conclusion 

 that they are the last remains of peculiar forms which have 

 everywhere else become extinct. 



Pemliarities of the British Flora. — Thinking it probable 



