NEW OR CRITICAL BRITISH ALGAS. 
21 
carpic conceptacles of that species. L. roseum is moreover a much 
larger and thicker species, the fronds often attaining a diameter of 
several feet and a thickness of from 3-4 mm. ; it also grows 
between tide-marks, while L. colliculosum appears to be a deep- 
water species. Specimens of L. roseum have been distributed in 
the sixth part of Mr. Holmes’s excellent “ Algae Britannicae 
Rariores Exsiccatas, ” an account of which will be found below. 
Pleurocapsa fuliginosa, HaucJc Meeresalgen Deutckland und Oester - 
racks , p. 515, jig. 231. 
Cell division taking place in all directions ; cells yellowish or 
reddish-brown, from 5-20 p in diameter, spherical or irregular in 
shape, with a thin investing membrane, solitary or united in 
clusters of 2-7 individuals. Cell contents homogeneous, break- 
ing up when mature into numerous spores. 
At Berwick this plant forms a thin brownish layer on rocks at 
high-water mark, and is usually accompanied by Calothrix scopu- 
lorum and other small algae. 
Aphanocapsa marina, Hansg. in Foslie Contrib. to Knowledge of Mar. 
Alg. of Norway., r ,,p. 169. Hauck and Richter, Phykotheka Univer- 
salis, x., No. 486. 
Cells roundish, seldom more than *5 p in diameter, blue-green, 
solitary or united in twos, in a colourless jelly. Cell membrane 
very thin. Layer dirty green, darker when dry. 
I have found this species at Berwick, where it appears to be not 
uncommon, growing on rocks at and above high-water mark, mixed 
with species of Calothrix and other small algae. 
Protococcus marinus, Kiitz . Phyc. Gener., p. 169. Tab. Phyc., I., t. 2. 
Cells mostly solitary, roundish, from 10-30 p in diameter. Cell 
contents brownish red, turning to a light greenish tint when dry. 
Mixed with Calothrix scopulorum, on rocks near high water 
mark. Weymouth. 
Protococcus ovalis, Hansg. in Foslie Contrib., i.,p. 159. 
Vegetative cells oval or elliptical, more rarely roundish, mostly 
5-10 p broad by 10-12 p long. Cell contents homogeneous, light 
green. Layer thin, dirty green. 
Weymouth. On rocks and stones at high-water mark and 
between tide marks. 
Plectonema terebrans, Bornet et Flahault sur quelques plantes vivant 
dans le test calcaire des mollusques in Bull. Soc. Bot. de France, t. 
xxxvi., pi. x., figs. 5 and 6. 
Filaments very slender, elongated, flexuous, commonly sparingly 
pseudo - branched, pseudo - branches most frequently solitary. 
Sheaths hyaline, very thin, cylindrical, not turning blue when 
treated with chlorzinc iodine. Trichomata pale green, not 
torulose, 0*95 p to 1*5 p thick; joints longer than the diameter 
of the trichomata, 2 p to 6 p long ; each dissepiment marked with 
two grains of protoplasm, apical cell rounded. 
