118 
NEW BRITISH FRESH WATER ALGJS. 
Polyediium minimum. Braun. P. pinacidium. Reinsch. Alg. FI. p. 80. 
Cells in front view tetragonous, margins straight or slightly 
repand, angles rounded, obtuse, unarmed ; cells from side view 
elliptical ; cells half the thickness of the transverse diameter. 
Size 6-9 /x x 3-6 /x. 
Lakes Clifden to Roundstone ; Oorid Lough ; Derryclare 
Lough. 
Polyedrium caudatum. Lagerh. Bidr. Sver. Alg. FI. West. p. 194. P. 
pentagonura. Reinsch. Alg. t. 3. f.2. 
Cells pentagonal, margins repand to emarginate, angles obtuse, 
each armed with a single long, firm, hyaline spine. 
Near Westport ; Lakes east of Lough Bofin. 
Anabaena (Sphaexozyga) oxthogona. West Linn. Journ., 1892, 195, 
t. 18,/. 8. 
Trichomes nearly straight, dispersed, dissepiments constricted, 
pale a^ruginous, joints subquadrate ; heterocysts globose ; spores 
twin or single, large, rather rectangular, 3-4 times as long as 
broad. 
Size. Veg. cells 5 /x diam. ; heterocyst 6-74 p; adult spore 
10-12 /x x 30-38 p. 
In peaty pools north of Cromagloun. 
The vegetative cells generally appear distinct from each other, 
being apparently connected by the mucilage ; the decidedly trun- 
cate spores, which are fully twice the diameter of the vegetative 
cells, are characteristic. 
Scytonema calotxichoides. Kutz. Rabh. FI. Fur. Alg. n., 253. West 
p. 196. 
Tomentose-CEespitose. glaucous Eeruginous, trichomes stout, 
more or less curved, intricate, distinctly or indistinctly articulate, 
pseudo-ramuli for the most part in pairs, spreading, variously 
curved, joints about equal in length and breadth, Eeruginous, 
granular, not torulose, terminal often un coloured, never red ; 
sheaths distinctly lamellose, colourless or spotted with yellow or 
pale brown ; resting cells interspersed, oblong-cylindrical, hyaline. 
Size. Without sheath 12^-13 /x diam. ; with sheath 17-20 /x 
diam. 
S. of Kenmare. 
Spixulina tuxfosa. Cram. Redwigia II., 61, t. 12, /.1. West p. 198. 
Solitary, pallid Eeruginous, trichomes for the most part abbre- 
viated. 
Trichomes 4|-5 /x diam. 
Near Westport. 
RXexismopaedia aexuginea. Breb. in Rabh. FI. Fur. Alg. ii., 57. 
West p. 199. 
Thallus somewhat limited and without colour. Families com- 
posed of 4-8-64 cells. Cells crowded, contents Eeruginous. 
Cells 4J-6 /x diam. 
Lakes Clifden to Roundstone. 
