CERAMIACEjE. 237 



Section 3. — Fronds without a distinct stem ; branches 

 scattered. 



Callithamnion floridulum. The little-florid Cal- 

 lithamnion. 



Fronds forming very dense, nearly hemispherical tufts, 

 very silky and slender, much branched in a forked or irre- 

 gular manner, level-topped ; branches few, long, erect, 

 straight, those in the lower part of the frond long, becoming 

 shorter above ; branchlets few or none, closely pressed to 

 the branches ; articulations three times as long as broad. 

 Favellse not known ; tetraspores tripartite, oval, on short 

 stalks, arranged on one side of the branches. 



On the west coast of Ireland large surfaces of rock are 

 covered with this plant, and it is washed on shore in 

 such abundance that the country-people use it for ma- 

 nure. It occurs in England, but is far from common. 



Callithamnion Rothii. Roth's Callithamnion. 



Fronds growing in dense velvet-like patches on the sur- 

 face of rocks, about half an inch high, very slender, level- 

 topped ; branches simple, erect, longest below, nearly bare 

 of branchlets ; articulations twice as long as broad. Tetra- 

 spores tripartite, two, three, or four together on the end of 

 a short branchlet near the tips of the branches. 



This very small and slender species grows on rocks 

 midway between high and low-water marks, or more 

 rarely almost beyond the reach of the tide. It is per- 

 ennial, and nourishes in winter and in cold climates. 

 The arrangement of the tetraspores is its distinctive 

 character. 



