"Specimens from Long Lake, in the collection of the Geological Survey of Canada, exhibit white crystalline limestone with light green compact or septariiform[W] serpentine, and much resemble some of the serpentine limestones of Grenville. Under the microscope the calcareous matter presents a delicate areolated appearance, without lamination; but it is not an example of acervuline Eozoon, but rather of fragments of such a structure, confusedly aggregated together, and having the interstices and cell-cavities filled with serpentine. I have not found in any of these fragments a canal system similar to that of Eozoon Canadense, though there are casts of large stolons, and, under a high power, the calcareous matter shows in many places the peculiar granular or cellular appearance which is one of the characters of the supplemental skeleton of that species. In a few places a tubulated cell-wall is preserved, with structure similar to that of Eozoon Canadense. [Footnote W: I use the term "septariiform" to denote the _curdled_ appearance so often presented by the Laurentian serpentine.] "Specimens of Laurentian limestone from Wentworth, in the collection of the Geological Survey, exhibit many rounded silicious bodies, some of which are apparently grains of sand, or small pebbles; but others, especially when freed from the calcareous matter by a dilute acid, appear as rounded bodies, with rough surfaces, either separate or aggregated in lines or groups, and having minute vermicular processes projecting from their surfaces. At first sight these suggest the idea of spicules; but I think it on the whole more likely that they are casts of cavities and tubes belonging to some calcareous Foraminiferal organism which has disappeared. Similar bodies, found in the limestone of Bavaria, have been described by Gümbel, who interprets them in the same way. They may also be compared with the silicious bodies mentioned in a former paper as occurring in the loganite filling the chambers of specimens of _Eozoon_ from Burgess." These specimens will be more fully referred to under Chapter VI. (D.) Additional Structural Facts.