CRYPTONEMIACE^. 191 



Furcellaria fastigiata. The pointed Furcellaria. 



Eoot fibrous ; fronds from a few inches to about a foot 

 high, cylindrical, repeatedly forked j branches all of the 

 same height, with acute axils and tips. Spore-clusters 

 formed from and embedded among the intermediate cells 

 of terminal, pod-like receptacles ; tetraspores zonate, scat- 

 tered among the external cells of similar receptacles. 



This species is very common. It grows on rocks in 

 tidal pools, is perennial, and fruits in winter. The 

 pods, which are formed at the tips of the branches, and 

 contain the spores and tetraspores, are very peculiar. 

 Their structure is similar to that of the rest of the 

 frond, but they are separated from it, as though by a 

 joint, and fall off when the fruit is mature, leaving the 

 branches truncated. In external appearance and struc- 

 ture this species resembles Polyides rotundus so closely 

 as to be with difficulty distinguished. The fructification 

 is however very different, and the root of the one is 

 fibrous, and of the other a disc; but this latter cha- 

 racter is not always easy to make out, or quite trust- 

 worthy. 



Genus LXXXVIII. GBATELOUPIA. 



Frond compressed or flat, membranaceous, pinnate, con- 

 sisting of two series of thread-like cells ; those of the inner 

 series densely interwoven, slightly jointed ; those of the 

 outer, or bark series short, necklace-like, horizontal. Spores 

 numerous, enveloped in a transparent, gelatinous membrane, 

 and immersed, in simple nuclei (favellse), just beneath the 

 external series of cells : these nuclei project slightly beyond 

 the surface of the frond, and are generally developed in 

 groups ; when mature, the spores are discharged through a 

 pore in the surface of the frond ; tetraspores cruciate, im- 



