114 ARCHER, ON PALMOGL@A MACROCOCCA. 
To this genus belongs clearly Palmoglwa Meneghinii 
(Kiitz.)= Penium Brébissonii (Ralts) = Cylindrocystis Brébis- 
sonit (Menegh.), the last being, doubtless, the correct apella- 
tion. And not less certainly, I believe, does Tiichodictyon 
ruprestre (Kiitz.) belong here. The species so named by 
KKiitzing I believe to be identical with Cylindrocytis crassa 
(De Bary) ; the remarkable mode of growth pointed out by 
De Bary* not being constant, seems to decide that it is not 
of sufficient importance to suggest the separation of this 
species from Cylindrocystis, seeing that the external structure 
seems to coincide. It is true, assuming that I am right in 
my identification of this plant, that Kiitzing places it ina 
genus by itself, distinct from his Palmogleea ; but the reasons 
for this course are not founded on any essential peculiarities 
of the cells themselves, or their mode of growth, but upon 
external accidental circumstances, which, so far as I can see, 
are in no way connected with the plant itself or its growth, 
and consequently erroneously introduced into his conception 
and definition of his genus. To indicate the circumstances 
on which Kiitzing relies for his generic distinctions, I cannot 
do better than repeat here his generic characters for Tri- 
chodictyon:}+ —“ Phycoma amorphum gelatinosum; substantia 
gelinea matricalis loculoso-vesiculosa; loculi fibris delica- 
tulis reticulatim fasciculatis circumtexti celluliferi.” It will 
be seen that Kiitzing relies here mainly for his generic cha- 
racters on the filaments accompanying the cells being imter- 
laced in a loosely reticulated manner, so as to leave white, 
roundish interspaces, in which occur the large ovato-elliptic 
cells, either singly or in one, two, or more pairs, surrounded 
by their broad and copious, finally confluent, gelatinous coat- 
ings. These filaments do not seem to differ from those 
frequently growing along with other Palmoglcean and other 
Palmellacean forms, nor do they seem organically connected 
with, or in any way belonging to, the plant im question. 
Similar filaments are by Kiitzing himself referred to Lepto- 
thrix, or perhaps to Hypheothrix. In fact, it would here seem 
as if it were only because these filaments often occur along 
with this plant in great quantity, penetrating through the 
mass, and because the cells themselves, during active vegeta- 
tion, increase vigorously from numerous centres, and copiously 
giving rise to their gelatinous investments (this taking place 
pretty equably over the mass), that the filaments are forced 
to give room, and become obliged to assume more or less of 
a reticulated disposition. But that these filaments possess 
no importance, nor any organic relationship, so far as I can 
* Op. cit., p. 37, t: vi, C., 4—6, 9. 
7 ‘Species Algarum,’ p. 250. 
