NEW OR CRITICAL BRITISH ALG2E . 
17 
Protoderma marinum, Rke. Algenji. p. 81. 
This species forms irregular closely adnate expansions, composed 
of a single layer of cells, on rocks near high-water mark. The 
cells composing the frond are roundish or slightly angular, and 
are arranged without apparent order. The plant is not uncommon 
at Cumbrae. 
Monostroma fuscum, Wittr. Monost. p 53, t. 4, fig. 13. 
Fintry bay, Cumbrae, on Chorda filum , etc., in sandy places, at 
low-water mark or beyond. E. B., Scarborough, G. Massee. 
Thallus somewhat rigid, a clear dark green when living, the 
colour changing in the Herbarium to a dirty brown. Cells angular, 
arranged without order, usually filled with starch grains, in section 
square or nearly so, 20-30 p in thickness. 
Acrochaete repens, Pringsh. Morph. Meeres. Alg. 
This plant closely resembles Bolbocoleon , from which it is dis- 
tinguished by the bristles arising directly from the ends of the up- 
right vegetative cells, and not from a bulbous base. Epiphytic on 
Leathesia, Cumbrae. 
Chaetomorpha linum, Kuetz. f. puvinata, Baft. Journal of Botany , 1892. 
Fintry Bay, Cumbrae. Not uncommon. 
This curious variety, which ( l.c .) I have referred to Ch. linum , 
Kuetz., differs so much in habit from the typical form of the species 
that I still entertain some doubts as to the correctness of the 
identification. The filaments are usually from 150 to 200 p thick, 
so that as regards size the plant might be either a slender form of 
Ch. area , Kuetz., or of Ch. linum, Kuetz. The former plant is 
usually found attached to the sides of rock pools near high-water 
mark, while the latter is always found unattached in extensive 
fleecy webs. The variety forms compact, cushion-like patches, 
several inches in diameter, over Corallina and other algae, in 
shallow sandy pools between tide marks, and, so far as I have ob- 
served, is never attached to the rock. Hauck and several other 
authors have expressed the opinion that Ch. cerea , Ch. linum , and 
Ch. crassa are but forms of one and the same species, and 
certainly this curious variety seems to be an intermediate form 
between the two former species. 
Ostreobium Queketti, Born, et Flah. Bullet. Soc. Bot. France , Vol> 
xxxvi. 
Cumbrae, Gare Loch. Not uncommon. 
One of the interesting class of perforating algse. The present 
species is very like Gomontia, from which it may at once be dis- 
tinguished by the fronds being unicellular. It appears to be not 
uncommon in shells, but as yet no undoubted reproductive organs 
have been found. 
Desmotxichum balticum, Kuetz. Sp. Alg. p. 470, BeinTce Atlas t. 12. 
On Zostera. Weymouth. 
This plant grows on zostera leaves in tufts, scarcely visible to 
the naked eye, and as it is, with us, usually accompanied by 
2 
