DICTYOTACEJE. 65 



This species delights in still, muddy bays, where it 

 sometimes attains the extreme size mentioned above. 

 It grows on rocks, and on Zoster a and algae. 



Asperococcus echinatus. Prickly Asperococcus. 



Fronds growing in dense tufts, from two to eighteen 

 inches long, and from one-tenth to half an inch in diameter, 

 tubular, tapering gradually at the base, then continuing of 

 the same diameter, and terminating in rounded or acute 

 points. Spore-clusters small, rough, spread thickly over the 

 whole frond. When young, the frond is covered with hair- 

 like fibres. 



Genus XXV. LITOSIPHON. 



Frond cylindrical, cartilaginous, without branches, formed 

 of concentric layers of cells. Fructification, naked spores 

 scattered over the frond, either singly or in clusters. — 

 Litosiphon, from the Greek litos, slender, and siphon, a 

 tube. 



The two species which constitute this genus are both 

 parasitical, and are pretty generally distributed wherever 

 the plants on which they grow occur. 



Litosiphon pusillus. Small Litosiphon. 



Fronds green, tufted, thread-like, from two to four inches 

 long, with a networked surface, covered with minute, jointed 

 fibres. 



This plant grows on Chorda filum and Laminaria bul- 

 losa, frequently clothing the frond of the former and 

 the stem of the latter for a considerable distance. Al- 

 though called the Small Litosiphon, it is many times 

 larger than its companion species. 



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