The Botany of Iceland - 01.12.1912, Qupperneq 68

54
H. JÓNSSON
of the coast. The percentage of each group is of the greatest im-
portance, and for the sake of expiicitness I have arranged these
figures in a tabular form, both those which refer to c and those
which refer to c + (c).
Species common to a 11 the coastal districts, given as
percentages.
Red Brown Green Blue-green All the groups
algæ algæ algæ alg'æ collectively €
20 27 19 17 22
38 70 82 100 60
On considering these two series of íigures it becomes evident
that the figures given for c + (c) come nearer to the real facts,
while those given for c merely indicate an incomplete knowledge
of the coastal distribution of the species. The fact is that, where
there is not a greater climatic difference between the different parts
of the coast than is the case in Iceland, it may always be expected
that, as regards the common species, the highest numbers will fall
to the green and to the blue-green algæ; and where the liydrographic
differences between the diíferent parts of the coast are as pronounced
as they are in Iceland, it is natural that the smallest number will fall
to the red algæ, and just as naturally the brown algæ will in this re-
spect be placed almost midway between the red and the green algæ.
Therefore, as regards the floristic difference between the different
parts of the coast, particular stress is laid on the remaining 76
species. In the following table they are arranged according to their
habitats. Under A, those species are given which either occur in E.
or N. Iceland only, or are most common there, and thence are dis-
tributed southward along the north-west coast as far as SW. Ice-
land. Under B are given species which either have been found in
S. or SW. Iceland only, or are most common there, and thence have
a distribution northward along the north-west coast, many of them
having, moreover, an eastward distribution along the north coast.
Table 2. The Distribution of the 76 species not common to ail
the coastal districts.
A ■3 ■s a ’o) o Z 1 iNW.Icel. SW. Icel. S. Icel. E. Icel. N. Icel. NW.Icel. SW.lcel. S. Icel. B
+ 1. Lomentaria clavellosa
+ 2. L. rosea
1. Lithothamnion flavescens JL i .. i.. .. + 3. Plocamium coccineum