528 VEGETATION OF BLAKENEY POINT. 
of which Cladonia rangiferina and Peltigera canina are the 
most conspicuous. 
Transition Flora. 
The transitions between dune and shingle already referred to 
are most frequent near the Headland. The dune species are 
represented by abundant Psamma, together with Senecio 
Jacobcea and Cerastium semidecandrum, all of which are 
common. Occasionally Erodium is present, and, more rarely, 
Carex arenaria. Arenaria peploides is also common, but is 
perhaps to be regarded as belonging equally to the one type of 
habitat as to the other. 
The shingle species proper are represented by one plant in 
abundance, viz., Silene maritima, and the occasional species 
are Anagallis arvensis, Atriplex patula, and Rmnex trigranu- 
latus. 
Situated near the Lifeboat House is an interesting depression 
bounded by lateral banks on either side and cut off from the 
sea by a third ; this is in process of passing into dune through 
the collection of sand around the low hummocks of Suceda 
fruticosa with which it is studded. At one point near the edge 
is a small association of Glaux maritima and Plantago 
Coronopus f. pygmcea ; these also occupy in part the channels 
between the hummocks, suggesting that the association had 
formerly a much greater extent, but is being driven out by the 
sand that accumulates above the shallow black mud which 
forms the soil of these depressions (shingle lows). 
Many of the hummocks are occupied by Silene maritima, 
whilst their slopes to the channels between afford support for 
Statice binervosa, from which situation the blown sand is 
rapidly driving it out. Between the hummocks, besides the 
plants already mentioned, Poa annua is present in considerable 
amount, and Frankcenia Icevis is occasionally found. 
(b) The" Long Hills." 
The “ Long Hills ” are a more advanced phase in dune 
fixation than those of the Headland, possessing a more extensive 
flora and a closer association of its members. As is usual at 
this stage, which is almost that of the “ Grey Dune,” lichens 
