240 MISS MARIETTA PALLIS ON THE 
metres (about 8 to 9 miles) from land where the murky waters of the Danube 
meet the clear waters of the sea. An interesting indication of the diminished 
salinity of the Black Sea close to land is afforded by the presence of small 
colonies of reed actually growing in the sea itself close to Sulina ; whilst 
the brackish-water Cirripede, Balanus improvisus, Darwin *, is attached to 
the under-water portions of the reed stems and rhizomes. 
The Balta comprises all the low-lying lands in Rumania overrun by the 
Danube floods, namely, the reed lands, water-meadows, and lakes, both of 
the river-valley and of the delta, and is, except for a few eminences— 
some of the grinds—flooded almost every year. The total area of the 
Rumanian Balta is about 891,000 hectares (about 34387 sq. miles), about 
400,000 T hectares (about 1543°75 sq. miles) of which are delta. 
There is between all portions of the Balta a certain similarity, but there 
are also conspicuous differences. The Balta of the upper portion of the 
river up to Tulcea presents in many ways a sharp contrast to the delta. It 
is subject to high floods, a large amount of silt is annually deposited there, 
and there are a considerable number of temporary and shallow lakes. It is 
a region of willow-forest [App. D, p. 276], of pasture, of reed-thicket 
(see PI. 28. fig. 1) which is swamp during part of the year only, and of reed- 
swamp which is permanent the whole year round, and Plav, except in the 
incipient form called Prundoae by the fishermen (see p. 245), is absent. 
The delta, on the other hand, isa region of comparatively low floods, the 
amount of silt annually deposited in its Balta is slight; and the lakes are 
for the most part permanent and comparatively deep. Willow-forest and 
pasture are practically absent, and intermittent reed-swamp 1 occurs only 
locally ; it is, in fact, a primitive region almost entirely covered by 
permanent reed-swamp and Plav (see Map, PI. 25). 
The average floor-level of the delta, the home оЁ Rumanian Plav, is about 
1'8 to 275 m. (about 6 feet to 9 feet) below low-water-level of the 
Black Sea, and is, except for the relief of a few embankments, shoals, and 
islands (the grinds of the fishermen), one huge sheet of water divided up 
into great and small lakes by the advancing reed-swamp which encroaches 
in many directions on the open water (see Map, Pl. 25). The commencement 
of the Balta lies here just behind the narrow sand grind which forms the 
present sea-beach, and is sharply marked out by the close ranks of 
* [ am indebted to Dr. P. P. C. Hoek, of Haarlem, for naming the Cirripede. 
+ See p. 2 of Antipa, “ Die Biologie des Donaudeltas und des Inundationsgebietes des 
Unteren Donau." Jena, 1911. 
i The soil of the intermittent swamp of the delta differs from that of the upper portion 
of the river. In the delta, if the intermittent swamp is situated near the beach the soil is 
sandy, but if inland, at the edge of the grinds, the proportion of organic matter may be 
considerable. On the other hand, the soil of the reed-thicket of the upper portion of the 
river is, almost entirely, flood-deposited river-silt : that is, fine inorganic soil. 
