123 
Thallus much branched, somewhat bristly and stiff, branches 
monosiphonous at the apices only; clothed with extremely 
regular corticating cells which may be overlaid by a 
system of irregular creeping filaments; branches pinnately 
arranged or whorled, some at least bearing a conspicuous, 
enlarged, apical cell, several times larger than the cell 
next below. Plants frequently bearing ease’ 
(Seesmote 7, Pp: ITE) Boe 15 
Plants completely hollow, at ieee mien seater : sie 
irregularly distended into spherical sacs, or elongated into 
tubular thalli branched only at the base ous 18 
Thallus of an organisation other than any included in the sere 
alternatives ah. aera 20 
Unilocular and (or) a ome sporangia as teal iene 
either stalked or sessile ... ies Sai Ectocarpus ...p.60 
Plurilocular sporangia as lateral appendages. Unilocular 
sporangia in pairs or whorls formed by transformation 
of lateral segments of the cells of the filament JIsthmoplea_ ...p. 64 
Unilocular and plurilocular sporangia in the course of the 
filament and not as lateral appendages... cas i. Sa. 2 
. Sporangia formed by transformation of series of consecutive 
cells of the filaments... ed Pylaella ...p.63 
Plurilocular sporangia in the course of the filament; large 
monospores formed singly or in pairs by transformation 
of certain cells of the filament ... ae Tilopieris ...p.75 
(See also Achinetospora, p. 75) 
Thallus forming crusts on rock ae 5 
Thallus forming discs, patches, sogeles ees or Sarshe file 
coverings to other algae ; 6 
Thallus quite inconspicuous, consisaine of eerkeay enced 
horizontal filaments creeping on or in the walls of larger 
algae or animals, giving off ie or hairs as upright 
branches ... ane is ee as = es ay eres 
Filaments creeping among the Pere cells Ms saice algae 
(Castagnea, etc.) or on animals (Flustva, Alcyonidium), 
giving off as upright branches sporangia and hairs .. 
Stveblonema. ...p.60 
(See note 4, p. r10 and also Ectocarpus parasiticus and 
Myrionema aecidioides) 
Filaments creeping within the substance of thick-walled 
Rhodophyceae such as Polysiphonia urceolata 
Mikrosyphay ...p.56 
Basal plate from which arise upright filaments closely pressed 
together; unilocular and plurilocular sporangia formed 
by direct transformation of apical cells of the filaments 
Lithoderma ...p.69 
Basal plate covered by pseudo-parenchymatous tissue, from 
which arises a covering of free filaments; unilocular and 
plurilocular sporangia as lateral branches from the base of 
free filaments arranged in sori ae se  alfsta’....p.69 
