The next in importance after those of Stennis among the Scottish group of circles is that at Callernish, in the Isle of Lewis. They are situated at the inner end of Loch Roag, on the western coast of the island, and consequently more remote from the routes of traffic or the centres of Pictish or Celtic civilization than even the Orcadian groups. The country, too, in their neighbourhood is of the wildest and most barren description, and never could have been more densely inhabited than now, which is by a sparse population totally unequal to such monuments as these. [Illustration: 89. Monument at Callernish. From a plan by Sir Henry James.] The group consists of three or four circles, situated near to one another, at the head of the bay. They are of the ordinary form, 60 to 100 feet in diameter, and consequently not remarkable for their dimensions, nor are they for the size of the stones of which they are composed. One of them, which had been covered up with peat-moss, was excavated some years ago, and a number of holes were found, filled, it is said, with charcoal of wood;[296] but the account is by no means satisfactory. About a mile to the westward of the three, on the northern shore of Loch Roag, stands the principal monument. This consists of a circle[297] 42 feet in diameter. In the centre of this is a tall stone, about 17 feet high, which forms the head-stone of a grave of a somewhat cruciform plan; but it is in fact only the tricameral arrangement common in tumuli in Caithness and other parts of the north of Scotland.[298] It apparently was covered originally by a little cairn of its own; but this had disappeared, and the tomb emptied of its contents at some period anterior to the formation of the peat which had accumulated round the stones, and which was removed a few years ago by Sir James Matheson when this grave was first discovered. From the central stone a double avenue extends 294 feet, and from the same point southward, a single row for 114 feet; making the whole length of the avenues 408 feet; while two arms extend east and west, measuring 130 feet across the whole.