ALGE, 
99 
terminated by a solitary sporangium. The unilocular sporangia 
are terminal, frequently solitary, but chains of 2-12 are sometimes 
found side by side with the solitary ones. 
Dr. P. Kuckuck considers this plant a sub-species of Pylaiella 
(Ectocarpus) litoralis ; M. Foslie, on the other hand, considers it 
a good species, which should be called P. compacta , as being 
identical with the old P. litoralis f compacta. M. Foslie remarks 
of it : “ On the other hand, P , litoralis f. compacta differs so 
much from the typical form of the species that it, as far as I have 
seen, deserves to be kept distinct. It is separated as to the habit, 
and, above all, by its ramification and solitary or short chains of 
sporangia, which are sometimes divided into two daughter-cells. 
I regard P. varia as a form of the species. It seems to possess a 
number of forms almost similar to that of P. litoralis In the 
paper above referred to, Mr. Holmes says : “ The limit of a species 
doubtless forms a very vexed question, but it seems desirable, for 
the sake of convenience, that when two plants differ in habit and 
mode of growth and development, so much as do P. litoralis and 
P. varia , and retain their characteristics in different countries, 
they should be kept distinct, as, for example, is done in the Rubi , 
Salices, and Hieracia , amongst Phanerogams. If Dr. Kuckuck’s 
plan were followed, there would be little reason for holding 
Ectocarpus distortus and Ectocarpus Landsburgii distinct from 
Ectocarpus tomentosus, Lyngb. The plurilocular fruits borne on 
specimens of E. Landsburgii , sent me by Mr. D. Robertson, of 
Cumbrae, and those of E. distortus, collected by myself at Fairlie, 
in Ayrshire, show so great a resemblance to those of E. tomentosus 
that I see no reason why they should not both be considered as 
sub-species of that plant, more especially as the differences in 
ramification and in the size of the zoosporangia are not greater 
than exist between P. litoralis and P. varia. A careful search on 
the West Coast of Scotland would, doubtless, reveal an inter- 
mediate series of forms connecting the three plants, Ect. 
tomentosus , E. distortus , and E. Landsburgii.” 
We cannot agree with Mr. Holmes in considering E. tomentosus 
nearly related to E. distortus. We have had ample opportunity 
of studying both species, and believe them to be as different from 
each other as any two species need be. The large, dense tufts, 
4-8 inches or more long, of E. distortus are of a dark chestnut- 
brown, and bear no resemblance to the light-coloured, rope-like, 
spongy masses, irregularly much-branched, of E. tomentosus. In 
the former species, moreover, the filaments vary in diameter from 
40-60 p, the average width of the principal branches being 50 p, 
while those of the latter are from 8-12 p broad. The plurilocular 
sporangia of Ect. distortus are ovate-acute, slightly truncated, 
while those of E. tomentosus are linear-oblong, straight or incurved. 
Ect. distortus appears to us to be very nearly related to Pylaiella 
varia, and we rather fancy Mr. Holmes must, through inadvertence, 
have written E. tomentosus for E. varius. A glance at the figures 
