(100) 



multifid ramuli, apices shortly forked, more or less incurved ; articula- 

 tions, near the middle, three to five times longer than broad, of the 

 ramuli and apices two to three times broader than long ; dissepiments 

 considerably swollen. Substance rather flaccid, more or less adhering to 

 paper in drying. Colour, a rather clear purplish red. Favellse small, 

 terminal or lateral on the ramuli, with two to four short involucral 

 spines. Tetraspores wholly immersed in the swollen joints, very con- 

 spicuous, triparted. 



This fine species has long been the lodestone around which, conglo- 

 merated as varieties, all the transparent jointed spineless Geramia took 

 refuge (several of which have now been clearly defined as distinct species). 

 It is at once conspicuous among the filiform Algse by its distinctly pellucid 

 articulations and dark coloured swollen dissepiments, visible even to the 

 naked eye ; than the last species, its colour is much paler, its stems less 

 cylindrical and much more swollen at the joints. Much assimilated in 

 habit to C. decurrens, it may at once be known from that species by the 

 narrow band of cellules across the dissepiment. 



In the present state of our knowledge of the species we are unable to 

 fix with certainty its geographical distribution, as other species are so 

 often sent under the names Ceramium strictum, ciliatum, and even 

 acanthonatum, for example. Judging from our own observation, we 

 would be inclined to conclude that it was not a common plant on our 

 shores, as we have only occasionally met with it. Its favoiu"ite habitat 

 seems to be deep worn rock-pools, where it generally lives as a parasite 

 on corallines or the smaller Algse, and when well grown, forms a beautiful 

 and very conspicuous object. 



EXPLANATION OF PLATE CIL 



Fig. 1. — Ceramium diaphanum, natural size. 

 2. — Hamulus with favelloe. 

 3. — Same, more magnified. 

 4. — Eamulus with tetraspores. 

 5. — Joint from same, more magnified. 

 6. — Tetraspore from same. All magnified. 



