288 MISS MARIETTA PALLIS ON THE 
PLATE 20. 
Fig. l.—Giant-reed Plav near Lake Lumina. Polystichum Thelypteris, Roth, sub- 
dominant. Note the rizak. 
Fig. 2.—A Plav of tall-slender reed. Near Balanova Sahi, near Lake Rosu. The 
height of the reed is about 5 m. (about 9 feet 10 inches). Note rizak (see p. 285). ' 
PLATE 21. 
Fig. 1.—Distant view of “ Sehwimmende Inseln " in Lake Merhei М. 
Fig. 2—“ Schwimmende Inseln ” at close range. Litcovu (Litcov) Canal. Between 
Carmen Silva and Litcov. Polystichum Thelypteris, Roth, subdominant. Swamp in the 
background with a Polystichum edge. In the water Nymphea alba, Linn., Stratiotes Aloides, 
Linn., Potamogeton natans, Linn., etc. 
The Norfolk reed and Fens. 
PLATE 22, 
Fig. 1.—Phragmites stools in Strumpshaw Broad, River Yare, Norfolk. The reed is 
Phragmites communis, Trin., var.?; Typha latifolia, and Glyceria aquatica, Wahlenb., are 
also present. The tree on the fen in the distance is Fraxinus excelsior, Linn. ; there are also 
some sallows on the fen—probably Salix cinerea, Linn. 
Fig. 2.—Sedge-fen at Breydon Horsey, Norfolk. Cladium Mariscus, В. Br., is dominant. 
The bush is Salix cinerea, Linn. The sand-hills show in the distance. July 21st, 1908. 
The Вайа in general. 
PLATE 23. 
Fig. 1.—The reed thickets of the Danube above the delta close to Tulcea; view of the 
Danube valley, taken from the upland at Somova. Salix alba, Linn., is very abundant. 
Fig. 2.—The beginning of a willow forest in the Danube north of Cernavoda (see 
Appendix B). 
PLATE 24. 
DIAGRAMS. 
Plavs of the Delta of the Danube (Sections L., IL., & ПІ.) and of East Anglian 
Fen (Section ТУ.). 1/40 natural size. 
The diagrams of Plav are drawn to the water-level of September 28th, 1918 (=zero) 
(see footnote on page 238). The difference in level of the water between Sept. 6th and 28th 
(approximately low and high water of the Danube) was about 0°55 m. (about 1 foot 10 inches). 
‘The upper line (black) of the diagram is the water-level of Sept. 28th, zero, and the lower 
line (dotted) that of Sept. 6th. The short dotted line below the Plav shows the position of the 
base of the Plav on Sept. 6th. The ground-bed of the delta is a silver sand sometimes over- 
laid by a layer of fine inorganic ooze which varies in thickness. Above the sand or inorganic 
ooze, as the case may be, there is generally a layer of fluvio-lacustrine ooze, viz.: an ooze 
with a considerable proportion of organic matter, which has probably mostly been added т 
situ to the fine river-borne silt. Above this layer is the free water in which the Plav floats ; 
the surface of the Plav rises a few centimetres above the water. The Plavs were sectioned 
with the rizak. An ordinary soil-borer about 20 feet (6:09 metres) in length was used in the 
fens for sounding, and for collecting small samples of ooze. 
