NEW OR CRITICAL BRITISH ALGiE. 
15 
diam.; repeatedly dichotomous, occasionally subpinnate below, tips 
scarcely attenuated ; air-vessels wanting ; receptacle dioecious, 
lanceolate, ovate, or globose, often 2-3 lobed, terminal on the 
ordinary branches or on short lateral shoots. Male receptacles 
much more numerous than female. 
Lying unattached on the muddy sand of a quiet land-locked bay. 
Loch Ranza, Arran, at half-tide level. David Robertson. 
Explanation of Plate 183. 
Fig. 1. Plant slightly reduced, showing its habit. 
,, 2. Portion of frond with terminal receptacles, natural size. 
,, 3. Portion of frond with lateral receptacles. 
„ 4. Oospore, x 200. 
„ 5. Group of Antheridia, x 200. 
Several papers dealing with the algal-flora of the British Islands 
have recently been published. In the “ Journal of Botany ” 
(March and June, 1892), I have described two new species, besides 
giving a list of the additions to the algal-flora of the Clyde sea- 
area, while in the “ Annals of Botany ” (July) and the “ Phyco- 
logical Memoirs,” Part I., I have described two more new species. 
Johnson in the “ Irish Naturalist,” Part I., mentions a new 
species, and several never before reported from the shores of the 
British Islands; Harvey-Gibson, besides some interesting “ Obser- 
vations on the British Marine Alga? ” (“ Journal of Botany,” 
April, 1892), gives in the transactions of the Natural History 
Society of Glasgow a useful list of the marine algse of the Oban 
district ; finally in his paper on the “ Parasitical Pha?osporea? ” 
(“ Journal de Botanique,” 1892) Sauvageau mentions that one of 
the species he there describes for the first time had been found on 
our shores, as well as those of France ; while Kjellman states that 
one of the new species described by him in his “ Handbok i Skan- 
dinaviens Hafsalgflora ” is met with in England. 
In the accompanying list I have gathered together the records 
scattered through these various publications, and in the hope of 
obtaining further information as to the distribution of the species 
on our coasts, I have added notes which I trust will enable those 
local collectors who do not possess the original descriptions to 
recognize the species mentioned. 
XVXicrocheete asiugenia, Batt. Journ. Bot. xxx., p. 86. 
Like the other species of Microchcete , this little plant, which is 
scarcely visible to the naked eye, bears a very close resemblance 
to some of the marine species of Calothrix , but its filaments never 
end in a hyaline hair as theirs do. From M. tenera , its nearest 
ally, it may at all times be known by the greater thickness of its 
filaments, 12 p (trichoma, 6-7 p), while those of M. tenera are 
6-7 p (trichoma, 5 p), and shortness of its articulations (about 
twice as broad as long) as well as by its marine habitat. It grows 
