the Marine Algce of the Firth of Forth. 445 



mickery. Dictyota dichotoma has also been recorded by 

 Ligbtfoot and Greville from the upper limits of this zone. 



There is here a curious commingling of Phaeophycese 

 and PihodophycefE, but it is at the same time of in- 

 terest to note the absence of the best stages of develop- 

 ment of some of those species of the latter possessing the 

 largest and most brilliant thalli (fi.f/., Nitophylla, Delesserice 

 — Ghylocladia clavellosa, &c.). . There is, on the other hand, 

 the introduction of several wine-coloured species (e.g., 

 Ceramium, FurceUaria, Poly ides, Polysij^ho^iia, &c.), and of 

 some of the more slender, often highly elastic olive-coloured 

 Cho7'dce, 



Just beneath the limit of extreme low water, and ex- 

 tending to a depth of from 1| to 2 fathoms, another area 

 may be distinguished, in which, however, not a few of the 

 former plants occur, and which corresponds to the boundary 

 between the Littoral and Sublittoral regions of Kjellman on 

 the Bohuslan coast. The species found in this area include 

 the following : — Bangia cilaris, Ahnfildtia plicata, Calli- 

 thamnion hrodicei, G, strictum, Chorda filum, Cordylecladia 

 erecta, Delcsseria alata, Corcdlina officinalis, Cladostephus 

 sjjongiosus, Cystoclonium purpurascens, FurceUaria fastigiata, 

 Gloiosiphonia capillaris, Grijithsia corallina, G. officinalis^ 

 Lithothamnion ijolymorphmn, Mesogloia vermicidaris, Poly- 

 siphonia elongata, Ptilota elegans, Rltodomela lycopiodioides, 

 Sphacelaria plumigera, Phodymenia palmata, &c. 



As this is the position in which the Cystoclonia are espe- 

 cially prominent on both coasts, from Dunbar seawards on 

 the south side and Kincraig to Fifeness on the north, it 

 seems right to designate it the Cystoclonium area. It ts 

 the representative of the Chaetoptcris formation on the 

 opposite shore of the North Sea, which is characterised by 

 the presence of Chaetoptcris plumosa associated with 

 Phloiospora tortilis (see page 441). 



In the more seaward parts — e.g., May Island, Bass 

 Kock, from Dunbar and Crail eastwards — a very varied and 

 rich growth of alga3 occurs between the limit of extreme 

 low water marks of spring and neap tides. Many of the 

 most beautiful forms of littoral Florideee are found here, as 

 well as a great variety of Phfeophyceffi. Alaria escidenta 

 is often w^ell developed, and bears copious fruit. Bangia 



TRANS. BOT. SOC. VOL. XVI. 2 G 



