16 
NEW OR CRITICAL BRITISH ALGJS. 
in stellate tufts on the fronds of Rhodochorton Rothii and R. flori- 
dulum in shallow sandy pools near high-water mark. Berwick. 
Brachytrichia Balani, Born, et Flak. Ann. Sc. Nat., 7 ser., Vol. iv., 
p. 372. 
This interesting species was discovered in February of the pre- 
sent year by Mr. G. Massee, at Bournemouth, on posts at half-tide 
level. The fronds, which somewhat resemble those of a Rivularia , 
are minute, seldom more than inch in diameter, gelatinous, at 
first globose and solid, then hollow and plicate ; in colour they vary 
from blackish to a dirty brownish-white, the filaments of which the 
frond is composed are simple towards the surface of the frond, 
but branched in a bifurcate manner below ; the heterocysts are 
intercalary, discoidal, and scattered without order through the 
filaments. 
Halosphaera viridis, Schmitz. Mitth. Zoolog. Stat. zu Neapel. Band 1, 
heft 1, p. 67-92, t. hi. 
In Part I. of the “ Irish Naturalist,” Prof. Johnson mentions 
that this curious alga was constantly present in tow net catches 
round the whole west coast of Ireland, even well out in the 
Atlantic, in one instance 27 miles west of Achill Island. Prof. 
Johnson further mentions that the alga has been found by Mr. J. 
D. Cunningham in Plymouth Sound. The plant in question is a 
very minute, green, globular mass, hardly as large as a pin’s head. 
The contents of this globular cell, by repeated bipartition of the 
cell nucleus, are transformed into very numerous daughter-cells, 
from which arise the zoospores. Prof. Schmitz remarks, in his 
account of the plant, that the formation of the zoospores differs 
essentially from that of the other green algae, in the fact that the 
zoospores do not arise directly through transformation of the 
daughter-cells of the original mother-cells, but are formed by a 
further division of these daughter-cells. 
Chlorochytrium dermatocolax, Reinke Algenfi. p. 88 . 
This curious algae forms longish, somewhat flattened, unicellular 
sacs, 20-30 p long by 15-20 p broad, in the cell-wall of Polyides 
rotundus , Polysiphonia elongata , etc. Cumbrae. 
Ulvella lens, Crouan Flor du Finist. p. 130, t. 9. ( Phyllactidium Lens). 
The species of the genus Ulvella are characterized by forming 
disc-like expansions which are composed of two or more layers of 
cells in the central portion, while the marginal part is monostro- 
matic. V . Lens forms roundish dark green expansions hardly 
larger than a pin’s head, which adhere by their entire under- 
surface to the substance on which they grow. These expansions 
frequently become confluent, and then the plant is more apparent 
to the naked eye. The cells composing the central portion of the 
frond are roundish and arranged without apparent order ; those of 
the margin are more or less angular, and arranged in regular rows. 
I have found the plant in considerable abundance on rocks, fuci, 
etc., at Cumbrae, Ayrshire, Heswall and North Kirby, Cheshire, 
and Point of Ayr, Flintshire. 
