ON TWO RECENTLY DESCRIBED MICE FROM ST. KILDA 137 



Mouse. Although we cannot expect to decide such questions from 

 a mammalian point of view alone, it is profitable to remember that 

 such "an old land extension connecting Greenland, Spitzbergen, and 

 Scandinavia with Scotland and Ireland " is relied upon by the editors 

 of the recently published second edition of the " Cybele Hibernica " 

 (Introduction, pp. li., Hi.) as the only reasonable explanation of the 

 presence in Ireland, and undoubtedly native there, of three plants of 

 North American habitat, two of which are unknown in continental 

 Europe ; nor would there seem to be any better explanation forth- 

 coming to account for our share in Ireland of Invertebrates l indis- 

 tinguishable from certain North American forms. 



Similarly Mr. A. H. Keane, 2 although writing on a widely 

 different subject, regards the " submarine bank, which stretches 

 from Scotland through the Faroes and Iceland to Greenland," as 

 representing a " vanished continent of great age, which would appear 

 to have still formed dry land in late Tertiary times." 



But the present paper deals not with the question of a submerged 

 Euro-American continent, but with the Mice of St. Kilda, and I 

 must content myself with pointing out in conclusion that the recent 

 expedition of exploration to Rockall, 3 the most westerly rock-islet 

 off the European continent, found that when trawling at a distance 

 of about 15 miles south of that rock, "the water shoaled to So 

 fathoms, and there was brought up in the net a most unexpected 

 assortment of shallow-water shells, evidently long since dead. 

 Amongst these were several kinds of Pecten, Venus casina, V. fasci- 

 ata, Mytilus modiolus, etc." In the words of the Rev. W. S. Green : 

 " How, under present conditions, such shells could be found living 

 anywhere on the bank was difficult to understand. It would seem 

 to afford the strongest confirmation to the theory that the time is 

 not so very long distant when there was more land, with a shallow 

 coast-line, and possibly extensive sandbanks, where now the pinnacle 

 of Rockall is the only speck acting as a memorial stone to what 

 tradition has called the ' Sunken Land of Buss.' After the shallow 

 sandbanks had vanished, these molluscs may have accommodated 

 themselves to a deeper sea than is usual for such organisms to live 

 in, and it may be that it is only now that the conditions are becoming 

 too severe for their further existence. There is, of course, the 

 possibility that these shells may have come from the bottom of 

 icebergs which had grounded in Greenland or Spitzbergen bays, but 

 I doubt if in times sufficiently recent such bergs have visited the 

 position occupied by Rockall, and therefore the former theory seems 

 the more probable. 



" The possibility of the shells having been brought as bait for 



1 See "Irish Naturalist," vol. iv. pp. 25, 122; vol, vi. pp. 225, 257. 



2 "Ethnology," 1896, p. 231. 



3 See "Trans. R. I. Acad.,' 1 vol. xxxi. pt. 3, pp. 45-46 (1897). 



