Io. 
ih. 
I21 
Plants usually unbranched, cells in regular longitudinal and 
horizontal rows, cells grouped in fours, each group surrounded 
by a definite membrane and embedded in a colourless matrix 
Capsosiphon aureolus ...p. 46 
Plants branched or unbranched, cells small and irregularly 
arranged 
Enteromorpha micrococca or young stages of other species ...p. 47 
Thallus discoid, closely applied to the thalli of other algae 
Pringsheimia  ...p. 45 
Thallus of microscopic filaments growing in or on animals, 
shells or other algae ask ae abe ate ae Bee AO 
Filaments embedded in shells... AAD Gomontia ...p.54 
Filaments immersed in the walls or creeping over the surface 
of animals (Flustra, Sertularia, Alcyonidium, etc.), or other 
algae Si aw ce zh ae Endoderma ...p. 49 
Thallus a plane membrane; or formed by compression of a 
tubular thallus... wate wats og : we a 8 
Thallus filamentous, cells mene or saedelete ate 
not completely coenocytic ee erty SE 
Thallus of various forms, built up of Me eeceer nee no 
cross-walls except where reproductive organs are found ... I1 
Thallus a membrane, one cell layer in thickness an Se 10) 
Thallus a membrane, two cell layers in thickness Ulva ...p. 48 
Thallus tubular throughout, flattened or cylindrical, branched 
or unbranched ... Ses eee a. nate eae aes 9 
Plants usually unbranched, cells in regular horizontal and 
longitudinal rows, grouped in fours, each group surrounded 
by a membrane and embedded in a colourless matrix 
Capsosiphon aureolus ...p.46 
Plants branched or unbranched, cells small and irregularly 
aimed) ahs eee Gee . Enteromorpha ...P.-47 
Thallus delicate in texture, tubular only when young, cells not 
shewing marked regularity in arrangement. Monostvoma ...p. 46 
Thallus a membrane usually only few cms. long, cells arranged 
in definite groups or packets embedded in colourless matrix 
Prasiola ...p.45 
Thallus of irregular coenocytic filaments, sparingly branched, 
not woven together to give a definite shape to the plant 
Vaucheria ...p.55 
Thallus of coenocytic filaments with a main axis and lateral 
branches more or less pinnately arranged ... Bryopsis ...p.54 
Massive thallus of sponge-like consistency, formed of interwoven, 
much branched, coenocytic filaments with dilated apices 
Codium ...p.55 
