152 МВ. A, D. COTTON ON CRYPTOGAMS 
A. MARINE ALGÆ.—In comparing subantarctie floras we find that not 
only have these been more thoroughly investigated, but, at the present at all 
events, they offer greater scope. Many of the large and showy Floride are 
restricted in their distribution, and hence a greater variety is found in the 
different parts of the whole region (cf. Lichens, p. 156). This may be partly 
owing to the dispersal of spores bsing due to ocean currents, the influence of 
these in bringing about a wide distribution being less effective than wind. 
Yet this alone cannot be responsible, as we find that the three main groups of 
algae differ amongst themselves in distributional range. This is shown in the 
following paragraph, where an attempt is made to give a general idea of the 
geographical components of the flora. 
(a) Analysis of Нота.— Аз a general rule, the Green Algæ, if the Siphoneæ 
be omitted, show a larger proportion of cosmopolitan plants than either the 
Reds or Browns. Species of Enteromorpha, Ulva, Cladophora, Rhizoclonium, 
Chetomorpha very similar to each other occur all over the world, though 
they are more abundant in temperate regions. In the Falkland Islands 
nearly half the species have a sufficiently wide range to be regarded as 
practically cosmopolitan. Of the remainder, the majority, though these 
include several unsatisfactory species of Cladophora, are only known from 
the subantaretic American region. The most interesting plants are the 
members of the Siphoniæ, namely, Bryopsis Rose apparently endemic to 
subantaretie America, the widely distributed Codium difforme, and C. mucro- 
natum, whose curious distribution is mentioned later (p. 165). Prasiola 
crispa, found in the colder and temperate regions of both the North and 
South hemispheres, is also worthy of note. 
In the Brown Algæ we have out of 41 species only 3 which are 
cosmopolitan (Pylaiella litoralis, Ectocarpus siliculosus, and Sphacelaria 
furcigera), and 3 which flourish in both north and south temperate 
regions (Phyllitis fascia, Scytosiphon lomentarius, and Desmarestia ligulata) ; 
though to these should be added the doubtful record of Punctaria plantaginea 
and another possible cosmopolitan in the presence of Colpomenia sp. The 
remainder, with the exception of Macrocystis (and the somewhat doubtful 
Chordaria), are confined to the southern hemisphere, and a large proportion 
do not occur north of the subantaretie regions. A few extend to South 
Australia and New Zealand, and others, favoured doubtless by the Humboldt 
current, occur on the west coast of South America. The distribution of 
Macrocystis, which is shared to a large extent by Jridwa cordata and 
Gigartina radula, is interesting and instructive. 
The Florideæ on analysis come out in very similar proportions to the 
Browns. About half out of 80 odd species are confined to the subantarctic 
or antarctic regions ; others extend as far north as South Australia and New 
Zealand, or advance up the Chilean coast; whilst 10 or 12 are cosmopolitan 
or at least occur very widely in temperate regions, The cosmopolitan species 
belong to the genera Porphyra, Ceramium, and Corallina, Gigartina radula 
