18 '2 Proceedings of the Royal Irish Academy. 



is no shadow of evidence to show that their importation was due to man, nor 

 is there any real evidence of iatrodnction by natural means : — 



^peeies wJiose means of Introduction are ZPnknown. 



Helicodonta persoaata Lam. — A dead example of this shell was picked up 

 in the sandhills at Xeweastle, in Down, by the late S. A. Stewart, in 1870. 

 Possibly sea-borne. 



Geiveral Distribution. — Central Europe, especially the mountainous districts 

 of eastern France, Germany, and Switzerland. 



HeUcella zaccarensis Kobelt. — A hali-grown living specimen of this rare 

 Algerian xerophile was taken by the wiiter near Eostrevor, iu Down, in 

 February, 1898. Origia unknown. 



General Distribution, — So far as is known at present, this shell is confined 

 to Mount Zaccar, ia Algeria. 



In the second group we have all those shells which are brought into this 

 country with merchandise. Most of these make then- appearance in nursery 

 gardens and hot-houses, where foreign plants are constantly aniving. Fi-uit 

 has also been proved to be a means of importation, thanks to the investigations 

 of Ml". W. A- Green. When introduced into hot-houses many of these shells 

 succeed in establishing themselves ; but so far we have no instance of any 

 foreign species becoming naturalized in the open air, except those which have 

 been introduced at Magheramome with railway ballast. As most of the aliens 

 come from a warmer climate than ours, this is not to be wondered at. In the 

 case of fruit, it is not usually tmpacked until it has arrived in a shop : and 

 therefore there is not so much likelihood of shells thus imported being able to 

 establish themselves. The list of species introduced by aiUficial means is, up 

 to the present, as follows : — 



Artificial Introductions. 



Testacella haUotidea Di-ap. — This species has recently been taken in a 

 garden at Strabane (^Tyione) by the Eev. A. H. Delap. Though future investi- 

 gation may prove it to be native, and Dr. Sc-haiff is inclined to i^aid it as 

 such, T think, judging by its distribution and that of the other membei-s of 

 the genus, that it is more likely to have been imported with plants. 



Agriolimax laevis Miill(?). — This slug, which has been foimd in many 

 greenhouses, differe from our native examples of A. laccis in its colom-, which 

 is of a peculiar slaty-purple tinge. Occurs in Dublin, Belfast, and at Castle- 

 wellan in Down. 



Hyalinia lucida Drap. — Common in the greenhouses at GlasneAin and 

 CastleweUan, and also in several private gardens near Bel&st. The Glasnevin 

 examples appear to resemble southern French rather than our native forms. 



