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 (Spheerococcus, 
Corallopsis, Phacelocarpus, and Calliblepharis) of the 
family have for the most part a similar distribution 
but are much more local. Spherococeus, 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. 
Rhodymentew. 
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 Plocamiwm 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 Rhodophycee built up of separate filaments, 
as Schmitz has established. By boiling a specimen 
in distilled water and afterwards pressing it under 
