indeed it is thought by some that it is the area in which megalithic
building originated. Morocco, Tunis, Algeria, and Tripoli all abound in
dolmens and other monuments. Even in the Nile Valley they occur, for
what looks like a dolmen surrounded by a circle was discovered by de
Morgan in the desert near Edfu, and Wilson and Felkin describe a number
of simple dolmens which exist near Ladò in the Sudan. Tripoli remains as
yet comparatively unexplored. The traveller Barth speaks of stone
circles near Mourzouk and near the town of Tripoli. The great trilithons
(_senams_) with holes pierced in their uprights and 'altar tables' at
their base, which Barth, followed by Cooper in his _Hill of the Graces_,
described as megalithic monuments, have been shown to be nothing more
than olive-presses, the 'altar tables' being the slabs over which the
oil ran off as it descended. True dolmens do, however, occur in Tripoli,
and Cooper figures a fine monument at Messa in the Cyrenaica, which
appears to consist of a single straight line of tall uprights with a
continuous entablature of blocks similar to that of the outer circle at
Stonehenge.

Algeria has been far more completely explored, and possesses a
remarkable number of megalithic monuments. Many of the finest are
situated near the town of Constantine. Thus at Bou Nouara there is a
hill about a mile in length which is a regular necropolis of
dolmen-tombs. Each grave consists of a dolmen within a circle of stones.
The blocks are all natural and completely unworked. The circle consists
of a wall of stone blocks so built as to neutralize the slope of the
hill and to form a level platform for the dolmen. Thus on the lower side
there are three courses of carefully laid stones rising to about five
feet, while on the upper side there is only one course. The diameter of
the circles varies from 22 to 33 feet. In the centre of the circle lies
the dolmen with its single long cover-slab. This usually rests on two