15 126 Proceedings of the Royal Irish Academy. 



between the Clew Bay and the East Anglian forms. 1 The specimens collected 

 by Ear at Chichester and referred to by Hudson in his original description 

 of F. vohibilis (Fl. AngL, ii., 1778) are unknown ; but there can be no doubt 

 that Miss Baker is correct in referring the twisted plant described by her 

 from Mersea Island and Blakeney to the Fucus volubilis of Goodenough 

 and "Woodward (1797), and of Turner (" Synopsis," 1S02), who cite it from 

 Erambridge Ferry and Wells, respectively — localities in the immediate 

 neighbourhood of those she has investigated. Several Erambridge Ferry 

 specimens exist, moreover, in the British Museum. 



The smaller forms of this same plant, F. volubilis Hudson, have, on 

 the other hand, often been referred to F. vesiculous var. balticus. At Mersea 

 Island, the dwarf forms are clearly linked by intermediates with the large 

 twisted forms ; but in Clew Bay it is otherwise, large plants being entirely 

 absent. This being the case, I have thought it best to use the name balticus, 

 which has already been employed for the Irish plant (Harvey, Johnson, 

 Batters). At the same time the whole question of F. balticus requires 

 investigation, as it is highly probable that more than one plant is included 

 under that name. Svedelius ( : 01) shows that several dwarf Fuci occur in 

 the Swedish Baltic, all of which he regards as varieties of F. vesiculvsus. 

 Before, therefore, the identity of our British plants can be settled, a careful 

 examination of Agardh's plants and fresh gatherings if possible from the 

 original locality are required. When the dwarf forms are not connected by 

 intermediates with normal plauts, there is great difficulty in ascertaining 

 from which species they are derived. The distribution of the cryptostomata 

 and the nature of the receptacles (if present) give the most hopeful clues, 

 whilst a careful study of the ecology of the plants should aid the elucidation. 



In Clew Bay var. balticus is usually found on the sides of narrow channels 

 and creeks on flat peaty areas. The flat surface of these areas is commonly 

 carpeted with var. muscoides, which grows densely crowded together, and is 

 of a short bushy habit. At the margins where there is more space, the plants 

 are longer and hang down. These marginal forms I refer to var. balticus. 

 The fronds are narrow. 3-4 inches long, slightly or not at all twisted, and 

 with cryptostomata for the most part marginal. They usually lie in the 

 channels, and are thus in contrast to the upright-growing muscoides. The 

 receptacles are small, seldom measuring more than Sxo mm. and often 

 less ; they are dioecious, not markedly mucilaginous, with non-projecting 

 paraphyses. Male receptacles are more frequent than female, but both are 



r. rolubilii is, without question, a curious salt-marsh variety of F. resiculosm ; and when the 

 systematic aspect of the British Fucaeeas is next dealt with, it will have to be placed under that 

 species. 



