I. Introduction. It is now two years since Mr. Horne and I communicated to this Society details of the discovery by the Geological Survey of Olenellus in the ‘Fucoid Beds’ and Serpulite Grit of the west of Ross-shire, which in our opinion proved the Lower Cambrian age of those strata. The discovery has been followed up by the Survey, and through the kindness of Major Robertson, the shooting tenant, and of Mr. A. P. Purves, the agent for Mr. Mackenzie, the proprietor of the Dundonnell Porest, facilities were afforded to Mr. A. Macconochie, Fossil Collector of the Survey, which allowed him to make a more exhaustive search of the localities mentioned in our paper. The search resulted in his obtaining a considerable amount of new material. while the work of the Survey was advancing in the region around the head of Loch Maree, prior to the discovery of Olenellus at Dundonnell, certain outcrops of the ‘Fucoid Beds’ were considered fossiliferous, and were accordingly marked off to be further searched by the collector. One of these, situated in Glen Cruchallie, more commonly, though erroneously, known as Glen Logan, yielded Mr. Macconochie specimens of Salterella and Hyolithes , but no recognizable fragments of trilobite. The other outcrop, noticed by Mr. Greenly, occurs on the northern slopes of Meall a' Ghubhais at a height of between 1200 and 1300 feet, just over the tree-line, and about 4 miles north-west of Kenlochewe. As this locality is situated in the Sanctuary, or most carefully preserved part