( 188 ) 



rosy pink, occasionally brownish, especially when old, very soon discharged 

 in fi'esh water. Favellse much less common than the tetraspores, lateral 

 on the branches, two or more together. Tetraspores terminal on the 

 Tiltimate pinniilse, veiy minute and solitaiy. 



Scarcely yielding in elegance to the last species, the present is almost 

 equally limited in its distribution, and scarcely more abundant in the 

 few localities where it has hitherto been found. It is also said to affect 

 similar situations to the last, namely, the bases of perpendicular, gene- 

 rally somewhat muddy rocks, at or a little beyond low-water mark, or 

 even occasionally a little above low water in deep, sheltered, rather 

 muddy pools, which are not too much infested with other Algae. 



The larger specimens closely resemble G. gracillhmim, but are seldom 

 so much tufted ; the main stem is generally percurrent, and the branch- 

 ing is always truly distichous. Like the last, its tetraspores are always 

 decidedly terminal, in which they differ from all the other species with 

 decomposite fronds. The favellse we have seldom seen, but the tetra- 

 spores are by no means scarce, and generally abundant when produced. 



EXPLANATION OF PLATE CXXVIL 



Fig. 1. — Callithamnion tJmyoideum, natural size. 

 2. — Pinnule with tetraspores. 

 3. — Pinnule with favellag. 

 4. — Tetraspore. 

 5. — Articulation. All magnified. 



