the Marine AUjx of the Firth of Forth. 449 



(even in muddy water in places sometimes under the in- 

 fluence of fresh-water rivulets at certain states of the tide), 

 G. pohjspermum, C. t2irneri, C. strictum. Ceramiurii acan- 

 tho7iotwm occurs here in very great abundance, e.g., espe- 

 cially on the steep sides of the Bass Eock and May Island ; 

 Ddesseria alata seldom occurs beyond the lower levels; 

 Cystocloniumpurpurascens is found, however, from Inchcolm 

 and Inchmickery eastwards. Chorda filum occurs, but is 

 comparatively stunted in growth ; on the other hand, 

 Chaetomorpha tortuosa is especially well developed in many 

 parts, as well as C melagonium. Some Desmarestice (e.g., 

 D. vlridis) are found growing here, especially towards the 

 eastern parts of the estuary, but after storms detached pieces 

 of this species, as well as of D. acideata, are very commonly 

 found among deposited drift-weed. Dictyosipjhon fcenicu- 

 laceus and D. hippuroides are especially characteristic of 

 this area and of the upper parts of that last mentioned. 

 Dumoiitia filiformis, as well as the crumpled variety in the 

 courses of fresh-water streamlets, is very common, and 

 some of the deeper Ectocarpi (e.g., F, fasiculatus and F. 

 granulosus) are frequent. Flachistea scutidata on Himaji- 

 thalia lorea is found at the lower reaches in tlie more sea- 

 ward parts. The Fuci (e.g., F. ceranoides, common near 

 Dunbar, F. nodosus, F. platycarpus F. serratus., F. vesi- 

 culosus) are all, with the exception of F. ceranoides in many 

 parts, very abundant, and from their well-marked size give 

 a characteristic appearance to the belt. Gelidinm corneum 

 is common and well developed, growing on a firm exposed 

 rocky substratum, but Griffithsia sctacca does not extend 

 mucli beyond the lower limit. Halidrys siliquosa is found 

 in shallow clear rock pools here, as well as in the Eutero- 

 morpha area, about to be referred to, and in deeper belts. 

 Herponema, velutina, which occurs not uncommonly on 

 Uimanthalia lorea^ is frequent in the seaward parts. The 

 Laurencice abound on many rocky shores, and especially 

 from Inchkeith to the east (e.g., L. 2>innatifida and L. 

 hybrida). llelohesice are not unfrequent — Lithothamnion 

 polymoiphum and 3IeIohesia pnstidata, both occur from 

 Inchcolm to the east. They are especially well formed in 

 places devoid of mud. Mesogloice (e.g., M, vcrmicidaris, at 

 the lower limits, andil/. virescens) ^ 3Iyrionemce {c .g. ,M .punc- 



