to be the simple dolmen with either four or five sides and a very rough
cover-slab. This and the upper part of the sides remained uncovered by
the mound of earth which was always heaped round the tomb. In later
times the dolmen became more regularly rectangular in shape, and only
its roof-block appeared above the mound. Contemporary with this later
form of dolmen were several other types of tomb. One was simply the
earlier dolmen with one side open and in front of it a sort of portico
or elementary corridor formed by two upright slabs with no roofing (cf.
the Irish type, Fig. 5, _b_). This quickly developed into the true
corridor-tomb, which had at first a small round chamber with one or two
cover-slabs, a short corridor, and a round or rectangular mound. Later
types have an oval chamber (Fig. 9) with from one to four cover-slabs or
a rectangular chamber with a long corridor and a circular mound.
Finally we reach a type where thin slabs are used in the construction,
and the mound completely covers the cap-stones: here the corridor leads
out from one of the short ends of the rectangular chamber.

The earliest of these types in point of view of development, the true
dolmen, is common both in Denmark and in South Sweden; only one example
exists in Norway. In Sweden it is never found far from the sea-coast.

[Illustration: FIG. 9. Corridor-tomb, Ottagården, Sweden.
(Montelius, _Orient und Europa_.)]

The corridor-tomb is also frequent in Denmark and Sweden, though it is
unknown in Norway. In Sweden it is, like all megalithic monuments,
confined to the south of the country. Of the early transition type with
elementary corridor there are fine examples at Herrestrup in Denmark and
Torebo in Sweden. A tomb at Sjöbol in Sweden where the corridor,
consisting of only two uprights, is covered in with two roof-slabs