240 CHAPTER III 



Colias nastes Bsd. S copula frigidaria Moeschl. 



Hillia iris Zett. Spaelotis clandestina Harr. 



Plusia, (Autographa) diasema Bsd. 



Araneae 



Bathyphantes puUatus Cambr. Hilaira frigida Thor. 



Estrandia grandaeva Keys. 



Apart from the inappropriateness of using the name "Amphiatlantic" for species 

 at the same time "Amphipacific", there are three reasons for excluding species 

 of this type from the group. — In xhe first place, it is usually impossible to declare 

 for certain that a considered species is actually lacking in Siberia west of the Lena 

 River; for instance this gap exists, according to our present knowledge, in the 

 otherwise probably circumpolar Carabid beetles Diachila arctica Gyll. and Elaphrus 

 lapponicus Gyll.— In the second place, a gap of distribution (also described, for 

 Lepidoptera, by Kusnezov, 1935) within the large West-Siberian plain, so different 

 from the mountainous region east of Yenisei, may be due to lack of conditions of 

 life; the limit between these regions corresponds to a rather sharp fauna! limit 

 {vide for instance Johansen, 1955). — In the third place, the western parts of 

 Siberia during Pleistocene time, and probably more than once, have been sub- 

 merged under water (Piroznikov, 1937) and an originally equal area of distribution 

 through northern Eurasia may have become interrupted thereby. 



These objections do not prevent particularly well investigated representatives 

 of this somewhat dubious type of Westarctic distribution being used as arguments 

 in the discussion of transatlantic faunal connections. 



The American element of the British flora 



The existence of a truly American element in the flora of Ireland, to a lesser extent 

 in western Scotland and in Wales, has long attracted the attention of botanists. 

 Though no quite corresponding faunal element peculiar to the British Islands is 

 known, the phenomenon has such a clear bearing upon our problem of possible 

 transatlantic connections that it should be briefly touched upon here. 

 The plant species involved are: 



Eriocaulon septangulare With. W. Irel. (widely); Inner Hebrides (Skye 



& Coll). 

 Limosella siihidata Ives S. & N. Wales. 



Myriophyllum alterniflorum americanum N. E. Ireland. 

 Pugsl. 



