(112) 



prominent, about half immersed in the outer edge of the dissepiments 

 of the upper forks. 



This species is readily distinguished from the preceding by the absence 

 of coloured cells from the greater portion of the articulation, and by the 

 pellucid, three-jointed spines, scattered all round the dissepiment, and 

 pointing in every direction. It does not seem to be at all a scarce 

 species, but from its being so often confounded with G. ciliatum and 

 other species, it is not easy to ascertain with anything like certainty its 

 true geographical range. Its nearest affinity seems to be C. ciliatum, 

 from which it may be at once known by the single-jointed spines point- 

 ing in every direction, and scattered all over the dissepiment, whilst 

 in that species they form a regular whorl round the middle, and mostly 

 point upwards. The fact of its being so often confounded with other 

 closely allied species, we do not consider so much depending on the 

 inaccuracy of observers as on their being led, by following the older 

 writers, to consider them all as only forms of one variable species. 



EXPLANATION OF PLATE CVI. 



Fig. 1. — Ceramium echionotum, natural size. 

 2. — Apex of a branch. 

 3. — Joints with tetraspores. 

 4. — A tetraspore from same. 

 6. — FaveUse, All magnified. 



