rhodomelaceje. 93 



the branches thickly set with alternate branchlets, which 

 are short and simple at the base of the branch, and become 

 gradually louger and more divided as they ascend. Spores 

 in roundish, stalkless conceptacles ; tetraspores in the 

 branchlets, near the top of the frond. I am, however, uu- 

 able to find any record of either spores or tetraspores on 

 British specimens. 



This is one of the most rare of our native Sea-weeds, 

 and has only been hitherto found at Bantry Bay and one 

 or two other localities in the south of Ireland, and on 

 the coasts of Devon and Cornwall. It is a summer 

 plant, and grows in shallow tide-pools. It requires to 

 be soaked for some hours in fresh water before being 

 laid down, or it will neither preserve its colour nor 

 stick to paper. I am indebted to my friend Mr. John 

 Gatoombe for a specimen of this rare plant, collected 

 by him at Plymouth. 



Rytiphloea thuyoides. Arbor-vitse-like Ry- 

 tipMoea. 



Fronds from three to six inches high, shrub-like, rigid, 

 growing in tufts, of a dark brownish-purple colour, striped 

 crosswise ; stems erect, cylindrical, rising from a mass of 

 creeping, fibrous roots, the lower part simple, the upper 

 part irregularly divided into alternate branches, the whole 

 covered with short, spine-like branchlets, those below sim- 

 ple, those above forkedly branched. Spores pear-shaped, 

 arranged in tufts, in egg-shaped, stalkless conceptacles, 

 which are usually very abundant; tetraspores tripartite, 

 in blunt, distorted branchlets. 



This species is pretty generally distributed round our 

 coasts, and is especially plentiful on the western shores 

 of Ireland. It grows on rocks, or on small sea-weeds 



