380 



singly in the axils of the branchlets. Excluding some rarer species 

 we mention one other example the broom-like S. scoparia, the 

 frond of which is coarse and very rigid, of a dark-brown colour, 

 two or three inches long, with the lower portion clothed by 

 woolly fibres. Its spores are arranged in clusters in the axils of the 

 branchlets. 



The last genus of the Ectocarpacece is Cladostephus, which grows 

 in dark-green tufts, usually five or six 

 inches long, in the deeper tide pools. 

 The fronds are cylindrical, branched, in- 

 articulate, and rigid; and the branch- 

 lets, which are short and jointed, are ar- 

 ranged in whorls. The spores are situ- 

 ated in short accessory branchlets, or in 

 masses at the tips of the ordinary 

 branchlets. C. verticillatus is a very 

 common species, the whorled branch- 

 lets of which are deciduous in winter, 

 when the accessory branchlets that bear spores begin to develop. 

 C. spongiosus is densely clothed with branchlets, and is of a bushy 

 habit, with a very spongy feeling. It is by some regarded as a variety 

 of C. verticillatus. 



The order Chordariacece is characterised by a compound 

 gelatinous or cartilaginous frond, consisting of interlacing horizontal 

 and vertical threads. The spores are not external as in the 



FIG. 265. Sphacelaria 

 radicans 



FIG. 266. Cladostephus 

 spongiosus 



FIG. 267. Chordaria 

 flagelliformis 



Ectocarpacece, but contained in cells in the substance of the frond. 

 In the typical genus the frond has a cylindrical, branched, carti- 

 laginous axis, surrounded by whorls of club-shaped threads and 

 slender gelatinous fibres. We have only one common species 



