224 SEAWEEDS 



wall. The gonimoblast itself is a much branched 

 tuft of closely packed filaments forming this convex 

 placenta, and the carpospores are produced singly 

 or in series on the points of the filaments at the 

 free surface of the placenta within the cystocarp. 



The Geographical Distribution is a very wide one 

 and the forms are more abundant in the warmer 

 seas, especially the two large genera Gracilaria and 

 Hypnea. The other notable genera (Spkcerococcus, 

 Corallopsis, Phacelocarpus, and Calliblepharis) of the 

 family have for the most part a similar distribution 

 but are much more local. Sphcerococcus, Gracilaria, 

 and Calliblepharis are represented in British seas. 

 Gracilaria lichenoides furnishes the substance called 

 " Ceylon moss " from which at least one kind of 

 Agar-Agar is prepared, a substance of much use in 

 the cultivation of Bacteria. 



Rhodymeniece. 



As in other families, so in this one, there is con- 

 siderable diversity in the vegetative characters. 

 Rhodymenia, of which R. palmata yields the edible 

 " dulse " of our coasts, and Plocamium have fronds of 

 conspicuous size, beauty, and firmness of texture, 

 while such genera as Chylocladia, Champia, and 

 Lomentaria with their hollow, tubular, and jointed 

 fronds represent a simpler type. Chylocladia is well 

 adapted to exhibit the typical constitution of the 

 thallus of Rhodophycece built up of separate filaments, 

 as Schmitz has established. By boiling a specimen 

 in distilled water and afterwards pressing it under 



