The principal groups are situated in Glen Malin More, a small valley running parallel to that of Columbkille, about two miles to the southward of it. There are three groups on the north side of this valley and two on the south, extending from about half a mile from the sea-shore to about three miles inward. The finest group is that next the sea on the south side, and consists of six dolmens, situated nearly in a row, about 50 or 100 feet apart, and is accompanied by some cairns, but so small as hardly to deserve the name of Tumuli. The stones of the dolmens range from 6 to 12 feet in height, and their cap-stones are still there, though some have been displaced. The second group, a little way up the glen, consists of ten dolmens arranged in two parallel rows, but they are neither so large nor so perfect as those nearer to the sea. Nearly opposite the first-named group on the shore, but on the north side of the stream, are two dolmens so nearly contiguous to each other that they may almost be considered as one structure. About half a mile to the east of this is a fourth group, consisting of four dolmens, accompanied by cairns, and two at least of the former are of considerable magnificence. The group farthest up the glen consists of five or six dolmens, but all except one in a ruinous state. The number of dolmens in Glen Columbkille is not given by Mr. Moore; but, from the context, there must be five or six, making up twenty to thirty for the whole group. So far as can be judged from the description, the group in Glen Columbkille seems to have better fitted and more complete chambers; consequently, I should infer it to be more modern than the others. It would, however, require careful personal inspection to classify them; though I have no doubt it could be done, and that, with a little care, these six groups could be arranged into a consecutive series, whatever the initial or final date may turn out to be. The general construction and appearance of these tombs is that of the so-called Calliagh Birra's house in Meath, described further on (woodcut No. 80). From its situation and appearance, there seems little reason for doubt that the Meath example belongs to the fifth or the sixth century; and if this is so, as little for doubting that these dolmens in Donegal are of about the same age, or, in other words, that this mode of interment continued to be practised in certain parts of Ireland, especially near the coasts, down to the entire conversion of the inhabitants to Christianity.