86 
W. Watson. 
the reduced amount of light. Aulacomnium palustre is abundant 
amongst the Sphagnum and is usually very slender and elongated 
with smaller leaves and fewer rhizoids than in the type. At the 
edges of the Sphagnum pockets, where it is less shaded and more 
liable to desiccation, it becomes more typical, being three to four 
times as broad and having numerous rhizoids. 
The alternation of these three facies seems to depend on the 
supply of fresh water. Where the water is continually being replaced 
Aneura pinguis and Pellia epiphylla (II A) are present, but when the 
water supply is intermittent and the water settles for some time 
the other facies of this zone are shown. The relations between the 
pockets of Sphagnum cymhifolium (II C) and the patches of Hypnum 
scorpioides (II B) are not so definite, and the uncertain evidence is 
not altogether en rapport with what has been observed in other 
districts. The pockets of Sphagnum cymhifolium are formed in 
depressions which are nearly always wet, and sometimes a metre 
broad, whilst the Hypnum scorpioides occurs in smaller patches in 
shallow peaty pools, the surfaces of which are above those of the 
interlinking channels, are liable at times to become flooded and in 
times of drought become dirty patches of moist peat which often 
coats the Hypna so thickly that they are scarcely distinguishable. 
The infrequency, smallness and indistinctness of these areas render 
a more definite correlation with the pockets of Sphagnum difficult. 
When the pockets consist of S. recurvum, as is not infrequently 
the case, they are more constantly wet than when formed of S. 
cymhifolium. 
III. Zone of Aneura multifida. The sides of the furrows just 
at the water-level are occupied by a very definite line of this thalloid 
liverwort with scarcely any admixture of other plants. It occurs 
immediately above the Aneura pinguis and Pellia zone (II A), and 
may even extend downwards into it, in which case the thalli change 
in character, becoming longer, narrower and less branched owing 
to their more aquatic and shady positions (Fig. 6 E). Where the 
facies of Hypnum scorpioides (I I B) or of Sphagnum cymhifolium (11 C) 
occurs, Aneura multifida may form the next zone in a wet to dry 
succession, but is not so definite as when it abuts directly on the 
Aneura pinguis and Pellia epiphylla facies (II A). The hepatic 
sometimes extends into drier zones and then becomes more tufted 
in character (Fig. 6 G). So far as it is at present known, this 
district is the only one in S. Somerset where A. multifida (so 
characteristic of the sides of moving water in uplands) occurs. 
