494 SMITHSONIAN MISCELLANEOUS COLLECTIONS [voL. 48 
introduction. The northern record of the three others, viz., H. 
(Dendrobena) rubidus (typicus), H. (B.) norvegicus and H. (B.) 
constrictus, is very dubious, in as much as it uncertain which of 
them, if more than one, occurs on Lavangsfjell in Tromsce Amt, 
and in Lofoten. However, as H. rubidus and H. constrictus belong 
to the most widely distributed species, their absence about Kristiania 
as well as in south and central Sweden, while occurring in Suldal, 
Stavanger and Bergen, in western Norway, is highly suggestive. 
The presence of one of these three in the province of Tromsce and 
in the Lofoten Islands, and, last but not least, the fact that one of 
them has had time to differentiate into a separable form, make it 
pretty certain that we have not to do with species introduced by 
man. Add to this the occurrence of H. constrictus in Britain and 
H rubidus in Iceland, and we have a distribution tallying very well 
with that of the other “ Atlantic” species. Considered by itself 
the case of these earthworms cannot as yet be taken as conclusive 
evidence in favor of a Scoto-Norwegian land bridge, because of the 
many uncertainties involved, but in connection with the rest of the 
biota it assumes enough significance to justify our calling attention 
tOcit. 
The land and fresh-water molluscs might also possibly furnish 
valuable data if their identity and distribution in west Norway were 
better known, especially as compared with the Scotch forms. At- 
tention is here only directed to Helix (Tachea) nemoralis which 
according to Miss Esmark (Journ. Conchol., v, October, 1886, p. 
108) is “ only found on the west coast’ of Norway, from Bergen to 
Stavanger. The species, it is true, is common in Denmark and 
rather common in the extreme southern province of Sweden, but 
becomes rare northwards, only reaching Goteborg on the west coast 
of Sweden and Jemtland on the eastern side.t It will be seen, how- 
ever, that the two habitats on the Scandinavian peninsula are widely 
separated. The distribution in the south and east shows the species: 
to have arrived there from central Europe over the Baltic land 
bridge, while its characteristic “ Atlantic” distribution in west Nor- 
way distinctly points to a land connection with the British Islands 
where it is widely distributed both in Scotland and Ireland. 
Under other circumstances the most convincing tests for uninter- 
rupted land connections are furnished by batrachians and fresh- 
water fishes. Unfortunately they are very slow travelers, especially 
the latter. The absence of evidence of any of them having crossed 
*Westerlund, Synopsis Molluscorum Extramarinorum Scandinavie, in 
Acta Soc. Fauna Flora Fennica, x11, No. 7, 1897, pp. 56-57. 
