350 BOTANICAL GAZETTE [APRIL 
grassland are frequently observed. A remarkable association is that of the 
limestone pavements, such as the 1911 party visited in western Ireland; these 
areas have much bare rock surface, and a most interesting vegetation, largelv 
mesophytic, is all but hidden in deep crevices. The chalk hills or downs, 
while resembling the older limestones, are characterized more by beech woods 
than by ash woods, though the latter are sometimes found. Another inter- 
esting type of the chalk is the yew woodland. 
The chapter on aquatic vegetation is by the editor, except for the part on 
the plankton, which is contributed by G. S. Wesrt, and the part on quickly 
flowing streams, which is contributed by Moss. Short chapters follow on the 
marsh formation and on the vegetation of peat and peaty soils, both by the 
_ editor. Miss PALtis, the efficient guide of the 1911 excursion in the Norfolk 
Broads, contributes a chapter on the aquatic and fen formations of that region. 
This chapter presents a district as a unit, the consideration of the physio- 
graphic development of the area being followed by a treatment of the aquatic 
formation and the fen formation with its various associations, and by a dis- 
cussion of the genetic relationships of the associations involved. 
Two chapters are devoted to the moor formation, the lowland moors being 
presented by the editor, assisted by RANKIN, and the upland moors by F. J. 
Lewis, C. E. Moss, and W. G. Smiru. RANKIN, who conducted the ro1t 
‘party to some of the Lancashire moors, considers the latter under the two 
heads of estuarine and lacustrine moors, the former being much the more 
extensive. While the heather, Calluna vulgaris, generally dominates the 
successional series, here it seems to culminate in a birchwood, but there are 
many examples of retrogression to heather moorland with birch stumps buried 
im situ. RANKIN considers also the valley moors of the New Forest, which 
were visited from Portsmouth at the close of the excursion. Upland moors 
were seen frequently during the course of the excursion, the foreign guests 
being repeatedly surprised at their vast extent, especially in habitats which in 
most parts of the world would be forested. That these were once forested, 
at least in part, was made evident again and again by the discovery of forest 
layers buried in the peat. Over vast areas the dominant plant of the upland 
moors is a cotton grass, Eriophorum vaginatum. In some places, especially in 
Scotland, there are extensive grass moors. Denudation and retrogression are 
frequently conspicuous. 
e chapter on arctic-alpine vegetation is presented by W. G. Sirs, 
who was the chief guide of the party in Scotland. The discussion is devoted 
chiefly to Ben Lawers, which was visited by the excursionists. The delimita- 
tion of formations here is more in harmony with that employed by most 
writers, the author distinguishing three formations near the summit: the 
arctic-alpine grassland formation, the formation of mountain top detritus, and 
the formation of arctic-alpine chomophytes (i.e., plants of rock ledges and 
fissures). The final chapter, prepared chiefly by the editor, considers the 
vegetation of the sea coast, the chief formations recognized being the salt 
