Mrs. Griffiths has for many years regarded the plant here 
figured, as being distinct from C. ci/iatum, from which the nature 
and disposition of the prickles that clothe the joints in greater or 
less number at once distinguish it. In C. ciliatum there is a 
regular whorl of stout three-jointed prickles, all pointing upwards, 
round the centre of every jomt; here we have several slender, 
one-jointed, needle-shaped prickles scattered regularly and 
pointing in various directions like the spines of a sea-urchin, a re- 
semblance which appears to have suggested the specific name 
under which Professor Agardh has described it. In young speci- 
mens the joints, at least the upper ones, are filled with a purplish 
fluid which makes the frond, while living, appear to be fully 
coloured, not diaphanous; when dried this fluid is dispersed and 
the true nature of the joint is obvious. Specimens from different 
quarters differ in some minor points, and possibly more than one 
species may still be confounded under this name, but the subject 
is one of great difficulty, and requires considerable observation of 
the living plant, durmg its whole course of growth. 
Fig. 1. CERAMIUM ECHIONOTUM; a tuft, of the natural size. 2. be x portion 
of a filament. 3. Apex, with tetraspores i situ. 4. Portion of a filament 
with involucres. 5. Involucre containing a bilobed favel/a. 6. A prickle. 
