498 MR. G. ERDTMAN : STUDIES IN THE 
S.W. Sweden were mapped, and comparisons made with the recent or 
sub-recent pollen-flora of the same district. 
Text-fig. 20, Nos. 3 to 8 show the mean pollen-spectra of that district 
at different periods [No.3 : pre-boreal spectrum (niveau 89); No. 4: late 
boreal do. (niveau 61) 5. No. 9: Atlantic, do. (niveau 55); No. 6: sub- 
boreal do. (niveau 39) i5 No. 8: subatlantic do. (niveau 11) ; No. 7: 
late subatlantic do. (niveau 3)]. The striking resemblance between No. 4 
(late boreal spectrum) and No. 3 (the A-zone of Scotland) is to be noticed, 
Salix and Coryles pollen are calculated separately. The percentage of the 
latter is greater in ‘Nos. 4 and 5.and smaller in Nos. 6, 7, and 8 than that of 
the mixed oak forest (elm, oak, lime). Because comparisons can easily be 
made, a great number of characteristic zones have been distinguished, each 
of which is marked by a special number. The above numbers (89, 61, 55, 
etc.) refer to these different zones. Von Post has made investigations, 
upon a large scale,-of peat mosses in the whole middle and south of Sweden. 
The results of these were. recorded in a paper read at the congress of 
Scandinavian naturalists. at, Gothenburg in the summer of 1923 (published 
in Geol. Foren. Förhandl. March 1924). Farther diagrams from more 
northern parts of Sweden (Helsingland) will be found in the paper by 
Halden, already mentioned (Halden, 1917), and the paper of Malmström 
(1923). The diagrams of the former are not directly comparable with those 
of von Post, “as the alder-pollen is calculated separately,  Malmström’s 
diagrams (Z. c. p, 148) show, among others, important percentages of Picea 
pollen. 3 
No. 10 shows the subatlantic spectrum from two high moors in 
N.W. Germany (Grienenwaldmoor an Borner Moor in the neighbourhood 
of Bremen). Alnus is unquestionably the dominant pollen, and this 
dominance extends also to the greatest part of the pre-subatlantie strata. 
No. 9 illustrates a general spectrum from a peat moss near Redkino, 
Government of Tver, Russia. It has been constructed by reference to a 
diagram published by,Gerassimoff (1923, fig. 0, 1, p 32). It is possible that 
the oldest postglacial strata are wanting. | 
Nos. 11 and 12, based upon the diagrams of figs. 72, 74, and 76 in Auer 
(1923), show mean pollen-spectra from northern Finland : the former gives an 
idea of the forest conditions after, the latter of the conditions before, the 
immigration of the spruce (the “abiegn” and “ pre-abiegn ” times 
respectively *). As to the deciduous trees, Auer has only counted the pollen 
frequency of alder and birch, other species being of very little importance. 
Rudolph and Firbas (1923) were the first to publish a pollen-diagram from 
a country south of the Baltic. No. 13 illustrates the subatlantie part of 
their diagram from the ‘ Sebastiansberger Heide " (Erzgebirge, Bohemia). 
* These terms are not good, as they cannot be used in the same sense in all countries 
where Abies occurs. 
