230 DR. F. J. LEWIS ON THE AECTIC BED PLAIS^TS, [June igi2, 



appearance of this material rather suggests the dung of some big 

 mammal. 



The presence of these plants at sea-level in the Lea Yalley 

 indicates a decided difference in climatic conditions from those of the 

 present day. 



At no place in the world do such plants as >Sa2ix Jierbacea, Betula 

 nana, and Fotentilla sibhaldi grow in quantity at sea-level along 

 the annual isotherm of 10° C. or the July isotherm of 17° C. Such 

 plants as SalLv herbacea and Betula nana grow abundantl}^ in 

 Iceland near or at sea-level, with a mean annual temperature of 

 4*41^ C. and a mean July temperature of 10° C. 



Doubtless, at the time when these plants lived in the Lea Yalley, 

 the British flora was poorer in species than it is now, and the 

 absence of competition may have allowed many of the Arctic and 

 Alpine species to linger on in the lowlands. But, after allowing 

 full weight to this possibility, I do not think it likely that such 

 plants as the Arctic elements in the list occurred at sea-level 

 under climatic conditions similar to the present. 



The position of the plant-bearing stratum in the river-gravels 

 indicates a late Glacial age for these remains, a period at any rate 

 considerably later than the retreat of the general ice-sheet of the 

 main glacial stages. This makes the find more interesting, and 

 tends to confirm evidence pointing to widespread Arctic conditions 

 from other sources in the north of Britain. 



The material does not in any way suggest the washed-out frag- 

 ments of a peat-bog, but rather resembles the drifted vegetation 

 from a tundra surrounding the spot where the fossils are now 

 found. 



Appendix II. — EepoPvT on the Mosses from the Aectic Bed. 

 By Hugh Neville Dixon, M.A., F.L.S. 



The moss-remains sent to me from the Arctic Beds at Bonder's 

 End represented four separate gatherings. The first was a general 

 collection from the deposit, while the others were taken from three 

 superimposed beds, and are referred to as the Upper, Middle, and 

 Lowest Beds. 



I have been able to determine with scarcely any doubt some forty 

 or more species. A certain number at present unnamed may yet 

 be determined, but these are so few that they cannot modify to 

 any appreciable extent the conclusions to be drawn from those 

 already determined. I give here a table showing the forms so far 

 detected, with their distribution through the different beds. 



The fragmentary or patchy nature of the three superimposed 

 beds left some doubt as to how far they represented different periods 

 of deposit, or how far one or other of the upper layers might be 

 simply a redistribution of the subjacent layers ; and also as to the 

 relation of any of them to the deposit from which the first sample 



