SCHARFF : DISTRIBUTION OF GEOMALACUS. 17 



NOTE OX THE GEOGRAPHICAL DISTRIBUTION OF GEOMALACUS 

 MACULOSUS, ALLMAN, IN IRELAND. 



By R. F. Scharff, Ph.D., B.Sc. 



Read June Wi, 1893. 



Carefitl descriptions of Geomalacus maculostis — one of the most 

 interesting of British terrestrial Invertebrates — have already been 

 published, but as only very few naturalists have seen the species in its 

 native habitat, a few remarks on its peculiar geographical distribution 

 may be of interest. 



This slug was first discovered in the autumn of 1842 in county 

 Kerry, by the late William Andrews, of Dublin, and was exhibited at 

 a meeting of the Dnblin Natural History Society — a society which 

 has since ceased to exist. 



The only definitely known locality in the British Islands for 

 Geomalacus macuhsus has hitherto been the neighbourhood of Lough 

 Caragh about 20 miles from Killarney, but Mr. Andrews is said to 

 have found it also on an island in Dingle Bay. A fact worthy of 

 mention is that this is also the only spot in Ireland where the 

 Natterjack Toad [Bufo calamita) has been taken, and careful search in 

 other places has hitherto proved unsuccessful in discovering this 

 Batrachian. In other respects the whole of the south-west corner of 

 Ireland shows a great sameness in the fauna and flora, both of which 

 are decidedly scanty as regards number of species, but the striking 

 Lusitanian affinities of some of the plants led the late Prof. E. Forbes 

 to the conclusion that a pre-Crlacial direct land-connection had existed 

 between Spain and that part of Ireland.^ In spite of the extreme 

 glacialists who hold that there was ice thousands of feet thick on 

 these parts of Ireland, I agree with Prof. Forbes in the belief that 

 the fauna and flora is of pre-Glacial origin and that they survived the 

 last glacial period on this spot where they once flourished. The 

 presence of these relics of a moister and probably warmer time may 

 be better explained and in a manner more in conformity with geolo- 

 gical evidences, by the supposition that they migrated across the 

 south-west corner of England at a period when Ireland was connected 

 with England and the continent of Europe by land, which to some 

 extent may have corresponded with the submarine 100-fathom plateau 

 stretching along the south-western coasts of the British Islands. 



A gradual extinction of this Lusitanian Flora is going on at the present 

 day. The groves of the strawberry tree [Arhdus unedo) existing a 

 couple of hundred years ago have dwindled down to a few stunted 

 and wretched specimens which may still be seen near the upper Lake 

 of Killarney, and at Glengariff , whilst other plants, like the Killarney 

 fern {Trichomanes radicans), are rapidly disappearing. It may be 

 supposed that Geomalacics ^naculosus, which has only been found in 

 Portugal besides the locality mentioned,^ migrated to Ireland along 



1 Mem. Geol. Surv. i. p. 347. 



2 It has lately been taken in N.E. France. — Ed. 



