An entirely different type of monument is found near Msila, south-west of Algiers. Here is a long low hill called the Senam, covered with large numbers of stone circles. These consist of large slabs of natural limestone set up on edge and not very closely fitted. The height of the slabs varies from 2 to 3 feet, and the diameters of the three still perfect circles are 23-1/2, 26-3/4, and 34-1/3 feet respectively. At a point roughly south-east there is a break in the circumference, filled by a rectangular niche (Fig. 19) consisting of three large slabs, and varying in width from 2 ft. 6 in. to 6 feet. There is a possibility that the niches were originally roofed, but the evidence on this point is far from conclusive. The interior of the circle is filled with blocks of stone, apparently heaped up without any definite plan. There seems to be no clue as to the meaning of these circles, as none have as yet been explored. MacIver and Wilkin are probably right in classing them as graves. [Illustration: FIG 19. Stone circle at the Senam, Algeria. (After MacIver and Wilkin).] The most famous, however, of the Algerian sites is unquestionably that of Roknia. Here the tombs lie on the side of a steep hill. They consist of dolmens often surrounded by stone circles from 25 to 33 feet in diameter. The cover-slabs of the dolmens usually rest on single uprights, and never on built walls. Several of the graves excavated contained more than one body, one yielding as many as seven. It is remarkable that three of the skulls showed wounds, the dead having been apparently killed in battle. Several vases have been found and a few pieces of bronze. We have seen that in some of the tombs of Bou Merzoug objects of iron were found. This makes it clear that some at least of the Algerian tombs belong to the iron age, i.e. that they are probably later than 1000 B.C., but beyond this we cannot go. The medal of Faustina sometimes quoted as evidence for a very late date proves nothing, as it is not stated to have been found in a tomb. There is no evidence to show how far back the graves go. It may be that, as MacIver and Wilkin suggest, the parts of the cemeteries excavated chance to be the latest. At Bou Merzoug the excavators worked chiefly among the graves on the plain and at the bottom of the hill. The more closely crowded graves which lie on the hill itself may well be older than these. In fact, all that may be said of the Algerian graves is that some are of the iron age, while others may be and probably are earlier. In Tunis the dolmen is not uncommon, and several groups or cemeteries have been reported. Near Ellez occurs a type of corridor-tomb in which three dolmen-like chambers lie on either side of a central passage, and a seventh at the end opposite to the entrance. The whole is constructed of upright slabs of stone, and is surrounded by a circle formed in the same way.