499 MR. G. ERDTMAN: STUDIES IN THE 
West of this peat moss on the shore of Garths Voe, N.W. of Laxobigging, 
is a salt meadow, the vegetation consisting only of Plantage maritima. A 
sample taken from highly-decayed dy-like substance 65 em. below the 
surface showed Alnus 0°75 per cent., Betula 96:5 per cent., Pinus 2 per cent. 
Quercus 0°75 per cent. ; Corylus 1:5 per cent. ; “Salie” 59 per cent. The 
excessively high pollen-frequeney (304) is noteworthy. It is clearly the 
result of two factors: a local Betuletum and an exceedingly slow growth 
of peat. 
5. THE POLLEX Frequexcy (PF) i THE PEAT MOSSES INVESTIGATED. 
In ‘Geologiska Föreningens Förhandlingar, Bd. 45, 1923, is a brief 
account of the pollen frequency in the Scottish deposits. It must be 
emphasised that the figures here published cannot be regarded as exact. 
Nevertheless they have a certain interest. For sedentary material the 
following pollen-frequeney numbers have been obtained :— 
The Shetlands....... lee sss 2 (text-fig. 19, 2) 
The Orkneys oo... 12 ( ., 19, 3) 
The Hebrides cn... 3 (y 19, 4) 
Isle of Lewis ............... 25 ( , 19, 5) 
Isle of Skye ............... ol ( , 19, 6) 
Ross and Sutherland ............... 192 ( , 19, 7) 
Helmsdale .................. ol Co, 19, 8) 
Strathearron ............... 13 (4, 19, 9) 
Achnasheen ............... 269 ( 4, 19, ro) 
N. Scotland and the Isles ......... (04 ( o, 19, 11) 
[ N.W. Germany (Erdtman, 1924). 335 (C, 19, 12)] 
The area of the circles in text-fig. 19 is proportional to the numbers giving 
the pollen frequency. There is also a circle, almost a point, which gives an 
idea of the PF of the Faroes (text-fig, 19, 1). The number (PF =0°34), which 
. > 2 23 
TExT-Fic. 19, 
*..0.. 
1 2 3 4 5 6 7 8 9 10 li 12 
is calculated from the table (p. 19) in the paper by Jessen and Rasmussen 
(1922), is not to be compared strictly with the figures from Scotland, because 
Jessen, who made the Faroe analyses, may perhaps have made preparations 
of a different thickness from those made by the author. 
Von Post (1916) and Hesselman (1916) have pointed out the desirability of 
making PF calculations based on a unit of volume, and the latter has given a 
short description of the manner in which this may be done. Prof, Lagerheim 
bas kindly drawn my attention to a paper by A. Meyer (1908), describing 
