, I4 Rhodora LJ?»« 



a. Filaments 30-40 it diameter. Cmmom. 



a " 50 u. diameter or more. 



h Older parts of the frond abundantly furnished with curved, hooked or 

 CirclnatC branches with verv acute tips; cells in older part of frond i-i 



.. 1 n r C SplttCSCOIS. 



b Hooked branches few or none; filament! usually Increasing In diameter 



upwards terminal cells blunt; more or less matted below by rhizoidal 



filaments. ,. ,. ,. . 



C Filaments about 60 ,1 below, 100 fi above; cells usually 2-4 diameters 



. C arc/a. 



c. Filaments about too » below, 150-250 ^ above; celU, except near the 

 tins, 4-1 4 diameters long. C ; *&*"?• 



d. Filaments slender, usually 40-60 »i diameter, pale green, densely inter- 

 woven into a spongy mass. c - «"'"'"• 

 d. Filaments free or somewhat interwoven, not spongy. « 

 e. Fronds attached onlv in the early stages, soon detached and forming 



dense floating masses in shallow warm water, 

 e Fronds remaining attached throughout the whole active lite. g 



f. Main filaments lOO-ISO » branches much smaller, divaricate; ultimate 

 • ,. 1 C. expansa, 



ramnli secuiul. , ' .„^ 



i Main filaments seldom over 100 p diameter, branches of successive 

 orders trraduallv smaller, ultimate ratnuli not conspicuously secund. 

 to J C.jracfa. 



B, Filaments and main branches usually under 100 p diameter. h 



■ u u « m " over 100 |x 



h. Fronds soft and silky, utterly collapsing when taken from the water. i 



h. " firmer. 



i. Cells 6-20 diameters long; plant of sheltered bays. 



C. Rudolphtatta. 



• « 2-6 " " ! usually in upper rock tide pools. 



C. glaucescens. 



i. Filaments short, rigid, more or less creeping; branches few. 



J C. Magnate hoc. 



i. Fronds freely branched. 



k. Branches 'recurved, pectinated with similar recurved branchlets. 



C. re fr acta. 

 k. BrandMS regularly flexuous throughout the frond. C.Jiexuosa. 



1. Filaments rigid; plants of exposed rocky shores. m 



1. Filaments not rigid. . 



m Filaments dark green, branches erect or appressed, opposite or 



, , , C. rupcstris. 



m Filaments lighter in color, ultimate ramuli blunt, short, densely 

 packed at the ends of the branches ; branching chiefly alternate. 

 1 C. laeterirens. 



„ Filaments 100-250 » diameter; ultimate ramuli stout, blunt, constricted 

 , ' C. Hutcktnsia*. 



at nodes. . , 



n. Filaments 40-150 » diameter ; ultimate ramuli slender, not constricted 



o. filaments with comparatively few main branches, beset throughout 

 with short, patent, often secund ramuli. C.htrta. 



Filaments much branched, branches of successive orders decreasing 

 In size, the tips set with series of secund, patent ramuli. C. gracilis. 



In considering the species in detail, it appears that the subgenus 

 Spongomorpha should rank higher than EucUdophora, the species 

 of the former having the branches differentiated, part being normal 

 and erect, part rhizoidal and descending; in some species there is a 



