13. 
14. 
15. 
16. 
be 
18. 
19. 
20. 
21. 
22. 
23. 
TRANSACTIONS AND PROCEEDINGS OF THE [ Sess. LXIX. 
U. subtilis, Kitz. O.—Near Kirkwall. S.—Bressay. 
Var. variabilis (Kiitz), Kirchn. O0.—Near Stromness. S.— 
Plankton of Lochs Brindister, Sandy, and Trebister; also of 
Neugles Water, and of Loch Beosetter, Bressay. 
Genus HORMOSPORA, Bréb. 
H. mutabilis, Bréb. O.—W. of Kirkwall. 
Genus URONEMA, Lagerh. 
U. confervicolum, Lagerh. Long. fil. tot. 55-450u ; crass. fil. 3°5-5y ; 
O.—Near Kirkwall, very abundant and epiphytic on Tribonema 
bombycinum (Ag.), Derb. and Sol. S.—Lerwick. 
Genus BINUCLEARIA, Wittr. 
B. tatrana, Wittr. O.—Hoy. S.—Lerwick ; Bressay. 
Family CH#TOPHORACES. 
Genus CH#TOPHORA, Schrank. 
Ch. pisiformis (Roth), Ag. S.—Near Lerwick. 
Genus MYXONEMA, Fries. 
M. tenue (Ag.), Rabenh. (Stigeocloniuwm tenue, Ag.). S.—Near 
Lerwick. 
Genus DRAPARNALDIA, Bory. 
D. glomerata (Vauch.), Ag. O.—Finstown. S.—Lerwick. 
Family MicROTHAMNIACES. 
Genus MICROTHAMNION, Nag. 
M. strictissimum, Rabenh. S.—Near Lerwick. 
Family TRENTEPOHLIACEZ. 
Genus TRENTEPOHLIA, Mart. 
T. aurea, Mart. O.—Near Stromness; near Finstown. S,—Near 
Scalloway. 
Order SCHIZOGONIALES. 
Family PRASIOLACEA. 
Genus PRASIOLA, Ag. 
P. crispa (Lightf.), Menegh. 0. and S.—Not uncommon. 
Order MICROSPORALES. 
Family MrcrospoRacEz&. 
Genus MicrospoRA, Thur. ; em. Lagerh. 
M. amena (Kiitz), Lagerh. O.—Hoy; W. of Kirkwall. S.—Near 
Lerwick. 
Some forms of this species were observed in which the cell-walls 
had become greatly thickened, the filaments presenting an 
irregular external surface. 
. M. pachyderma (Wille), Lagerh. O.—Hoy; W. of Kirkwall. 
