SECT. ii. SPH^ZROCOCCOIDEJE. 239 



disc, and spreads widely into a flat ribless expansion, 

 more or less deeply slit into broad rounded divisions. 

 Wavy nerves from the top of the stem spread through 

 the fronds, which are left bare in winter, and give rise to 

 new fronds in spring. The leaves of the Delesseria san- 

 guinea, from two to eight inches long and from one to 

 six inches broad, are of the richest colour and most 

 delicate structure, with evenly curle.d edges, and a firm 

 solid stem, with prominent midrib and nerves. In winter 

 globose stalked spore conceptacles are borne on the 

 skeleton midribs of the summer's leaves from which 

 the margin has decayed, which thus become the stems 

 of the next year's plant. In this plant tetraspores 

 in small special stalked leaflets fringe the skeleton 

 midribs; in the Mtophyllums they are either scattered 

 in dots over the frond, confined to the centre, or in 

 lines round the margin. As regards the internal struc- 

 ture of this order, nothing can be more various, but 

 they never acquire a truly articulate form. The genera 

 and species of this group are widely distributed; 

 they have many representatives in the Mediterranean. 4 

 The genus Sphserococcus is confined to Europe, while 

 numerous genera are exclusively tenants of the southern 

 hemisphere. The Gracilaria lichenoideg, the Ceylon 

 moss, is celebrated for its gelatinous qualities ; and the 

 Gracilaria compressa on our own shores is excellent as 

 a pickle or preserve, and very ornamental. One of the 

 most beaxitiful Algse known is the Grinnelia americana, 

 which abounds on the eastern coast of North America ; 

 fig. 24 6, is a vertical section of its conceptacle, showing 

 the rudimentary placenta and spore threads. It dif- 

 fers singularly from the Delesseria sanguinea, of which 

 it is an exact analogue, in the capsules being scattered 

 over the surface of the frond instead of being situated on 



4 ' Flora Italica Crypta.' 



