CRYPTONEMIACE^E. 189 



logists." And again, in another letter, received a fort- 

 night later, he writes : — " On Friday I succeeded, after 

 wading np to my waist, in reaching the rock on which 

 Chrysymenia (Chylocladia) rosea grew, and found the 

 plants so altered in appearance that I hardly knew them ; 

 they had become so spiry, and altogether different in 

 form and colour, that they did not deserve the name of 

 rosea at all. However, you will now be able to describe 

 the full-grown plants from the specimens I intend to 

 forward in a few days." C. rosea is said to be annual, 

 and to grow on rocks and Algse in deep water, and it is 

 evident from the above account that it likewise grows 

 between the tide-marks. Orkney and Filey are recorded 

 as habitats by Dr. Harvey, and to these Plymouth must 

 be added. 



Genus LXXXVI. HALYMENIA. 



Frond cylindrical or flat, gelatinous or fleshy, forked or 

 pinnate, consisting of a thin double membrane, composed 

 of small, coloured cells, and separated internally by jointed, 

 branching fibres, Spores minute, densely packed, enclosed 

 in a transparent sac, which is immersed in the frond imme- 

 diately beneath the surface ; tetraspores cruciate, and scat- 

 tered among the surface cellules. — Halymenia, from the 

 Greek als, the sea, and umeen, a membrane. 



The specimens included in this genus are all of a beau- 

 tiful rose-colour, and delicate gelatinous substance ; only 

 one is found on our coasts, and that but sparingly. 



Halymenia ligulata. The strap-shaped Halymenia. 



Boot a small shield ; frond from a few inches to a foot or 

 more long, and from an eighth of an inch to two inches 



