Professor Hall having kindly presented some good specimens to the Peter Redpath Museum, I have had sections made, and have thus been able to verify his description, and to compare the structures with those of some of the more ancient Stromatoporoid specimens in our collections, including the Archæozoon from New Brunswick, of which Mr. Matthew has presented a fine slab to the Museum. I have also, through the kindness of Professor Winchell, been enabled to compare these with his _Cryptozoon Minnesotense_, and Dr. Walcott has added specimens of his Stromatoporoid forms from the pre-Cambrian beds of Arizona. It would appear from these and other specimens in our collections from the Cambrian and older Ordovician beds, that we have here an ancient type of Stromatoporoid organism in which the original laminæ seem to have been thin and coriaceous, without apparent pores or pillars connecting them with each other, but having between them relatively-thick layers of fine fragmental matter penetrated by numerous irregularly tortuous and branching tubes. The laminæ often present a carbonaceous or chitinous appearance, though frequently replaced by mineral matter, and the intervening layers show both a calcareous and carbonaceous substance, with much fine silicious sand often as rounded grains, and apparently some dolomitic granules. The tubules seem destitute of any distinct wall, otherwise the whole would resemble on a large scale the nodular and laminated masses of _Girvanella_, which Wethered has described as surrounding organic fragments in Silurian and Carboniferous and Jurassic limestones in England.[55] [Footnote 55: British Association, Liverpool meeting, 1896.] The _Streptochetus_ of Seely from the Chazy limestone[56] is evidently very near to Girvanella, if not generically identical, and I have a similar species from the Lower Cambrian pebbles in the conglomerates of the Quebec group. In all these forms, however, the thicker or intermediate laminæ seem to consist wholly of definite convoluted tubes, whereas in Cryptozoon the tubes, or tubular perforations, are separated by a mass of material which in the best preserved specimens seems to consist of a fibrous stroma including calcareous and silicious particles. It seems doubtful to what class of beings such a structure should be referred; but whatever its nature, it evidently had great powers of growth, and seems to be a very ancient form of life. [Footnote 56: _Amer. Journ. of Science_, 1885. See Nicholson, "Manual of Palæontology," ed. of 1889.]