Among other indications of fossils in the Laurentian rocks, mentioned in my paper on the structure of Eozoon , are certain perforations resembling burrows of worms, found in a calcareous quartzite or impure limestone from Madoc, in Upper Canada. They occur in specimens in the Museum of the Geological Survey, and also in specimens subsequently collected by myself at the same place. The beds at Madoc, containing these impressions, underlie, unconformably, the Lower Silurian limestones, and are regarded by Sir W. E. Logan as belonging to a somewhat higher horizon in the Laurentian than the Eozoon Serpentines of Grenville. They are also less highly metamorphosed than the Laurentian rocks generally. They are described in Sir W. E. Logan's Report on the Geology of Canada, 1863, at p. 32. The impressions referred to consist of perforations approaching to a cylindrical form, and filled with rounded siliceous sand, more or less stained with carbonaceous and ferruginous matter, more especially near the circumference of the cylinders. These superficial portions being harder than the containing rock, and of darker colour, and also harder than the interior of the cylinders, project as black rings from the weathered surfaces; but in their continuation into the interior of the mass, they appear only as spots or lines of a slightly darker colour, or stained with iron-rust. When sliced transversely and examined under the microscope, they appear as round, oval, or semicirenlar holes drilled through the rock, and lined around their circumference with dense and dark-coloured siliceous matter, while