fronds may be easily distinguished with the naked eye in
spite of their smallness, their green colour trenching upon the
discoloured parts of the plants upon Avhich they are fixed.
A t first sight one might he induced to believe that they are
but parts of those plants Avhose chromule has not been disorganised
by the immersion which has discoloured their other
parts. These rosettes follow the forms of their supports. I
have seen them upon Conferva fracta ; they then embrace the
filaments in such a manner as to surround them with a sort
of ferrule or annular hood. A slight magnifying power of
the microscope is sufficient to show the elegant disposition of
radiating filaments which, by their approximation and lateral
union, resemble an areolated disc, which recalls to mind certain
Pediastra belonging to the Desmideæ.
“ The fronds are roundish, from one to two, rarely three mil-
lemetres in diameter ; they are formed of filaments closely applied
to the plant on Avhich they grow, dichotomously branched;
branches approximate, and as though soldered the one to the
other. The articulations or cells three or four times as long
as broad, often unequal, are furnished interiorly with a green
granular endochrome. On a great number of these articulations
is remarked a tubercular rounded projection or protuberance,
from which arises a tubular filament, truncated a
little, dilated at the summit, from the interior of which issues
a long and very delicate thread. This part of the organization
of this Alga shows clearly tha t it ought to be placed in
the Choetophoroideoe, and near to Bulbochoete. This setifer-
ous sheath is very caducous and difficult to perceive.
“ A t a certain period of the existence of Coleochæte scutata
its disc is covered here and there with tuberculated masses of
endochrome, which one might regard as the formation of
spores, at a later period indeed, these little masses are converted
into groups of globules charged with the tube or seti-
ferous sheath which characterizes this Alga. In the first
period of its developement, the tubes terminate in a point,
from whence issues a long setaceous filament of great tenuity
; at a later period, the summit of this sheath is open,
and appears then truncated and slightly dilated.
“ About the globule which is at the base of this sheath, are
developed, in the form of a rosette, the first articulations of
the filaments, as is seen in fig . 7. They are cuneiform ; some
slightly bi-lobed, give origin to two cells, and so determine the
dichotomy of the filaments.
“ The variety, fl soluta, which I have sometimes found
amongst examples of the ordinary type, might be considered
as another species on account of its filaments, which are not
depressed, and are free in their whole length, but certain
fronds of the ordinary type may be regarded as connecting
the two forms ; I therefore do not think tha t they can be
separated. I have always observed tha t the filaments of the
variety fl do not preserve, in ramifying, a dichotomous disposition
so exact as in Coleochæte scutata, &c.”
In all those specimens of this most interesting production
which I have examined, the sheaths and cilia have been altogether
Avanting. In some cases, however, the point of
attachment of the sheaths to the cells could be perceived.
The natural position of the genus is certainly near to Bulbochæte.
S ub-fam. ii. Ul o t h r ic e æ .
20. LY N G B Y A Ag.
Char. Filaments simple, subulate, and shining. Zoospores
several in each cell, escaping through rents in the walls
o f the cells.
Sphoeroplea Berk. Ulothrix Kfitzing, Phyc. Gen. p. 251.
Sphoeroplea Kiitzing, 1. c.
Name in honour of M. Lyngbye, author of an excellent
work on the Algæ of Denmark.
The genera Lynghya and Sphoeroplea are undoubtedly
identical, and one of the terms must of necessity be suppressed.
Bangia also differs but slightly from the genus
Lynghya, and its abolition seems called for. Kiitzing has
constituted a new genus for the reception of Conf. zonata
{Sphoeroplea crispa'^Qvk.), Ulothrix, preserving also the genus
Sphoeroplea, the type of which he makes Conf. annularia Roth.