requently. To the north-east of the Dinaric Alps extends a region of
mountain, moor and forest, with deeply sunk alluvial basins, which
finally expand into the lowlands of the Posavina, or Vale of the Save,
forming the southernmost fringe of the Hungarian Alfold. Bosnia belongs
wholly to the watershed of the Save, and its rivers to the Danubian
system, no large stream finding a way to the Adriatic. The Save flows
eastward along the northern frontier for 237 m. It is joined by four
main tributaries, the Drina, Bosna, Vrbas and Una. The Drina is formed
on the Montenegrin frontier by the united streams of the Tara and Piva;
curving north-eastwards past Visegrad, it marches for 102 m. with
Servian territory, and falls into the Save at Racha, after a total
course of 155 m. The Bosna issues from many springs near Serajevo, and
winds for 107 m. northward, through a succession of fertile glens,
reaching the Save 1 m. west of Samac. Farther west, the Vrbas cuts a
channel through the Dinaric Alps, and, after passing Jajce and
Banjaluka, meets the Save 94 m. from its own headwaters. The Una rises
on the Croatian border, and, after skirting the Pljesevica Planina, in
Croatia, turns sharply to the north-east; serving as a frontier stream
for 37 m. before entering the Save at Jasenovac. Its length is 98 m. At
Novi it is joined by the Sana, a considerable affluent.

Herzegovina, which lies south of Bosnia, in a parallelogram defined by
Montenegro, Dalmatia, the Dinaric Alps, and an irregular line drawn from
a point 25 m. west-north-west of Mostar to the bend of the river
Narenta, differs in many respects from the larger territory. Its
mountains, which belong to the Adriatic watershed, and form a
continuation of the Montenegrin highlands, are less rounded and more
dolomitic in character. They descend in parallel ridges of grey Karst
limestone, south-westwards to the sea; their last summits reappear in
the multitude of rocky islands along the Dalmatian littoral. As in the
peaks of Orjen, Orobac, Samotica and Veliki Kap, their height often
exceeds 6000 ft. West of the Narenta, their flanks are in places covered
with forests of beech and pine, but north-east of that river they
present for the most part a scene of barren desolation. Their monotony
is varied only by the fruitful river-valleys and _poljes_, or upland
hollows, where the smaller towns and villages are grouped; the districts
or cantons thus formed are walled round by a natural r