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All the trees have large spreading roots, solid and strong, sometimes branching, and traced to a distance of several feet, and presumed to extend much farther. In a colliery near Newcastle a great number of Sigillariae occur in the rock as if they had retained the position in which they grew.
Stigmaria ficoides, Brong. 1/4 natural size. Stigmaria ficoides, Brong. Surface of another individual of same species, showing form of tubercles. In the sea-cliffs of the South Joggins in Nova Scotia, I examined several erect Sigillariae, in company with Dr. Dawson, and we found that from the lower extremities of the trunk they sent out Stigmariae as roots.
They probably fell in successive generations from natural decay; and making every allowance for other materials, we may safely assert that every foot of thickness of pure bituminous coal implies the quiet growth and fall of at least fifty generations of Sigillariae, and therefore an undisturbed condition of forest growth enduring through many centuries.
Further, the Sigillariae grew on the same soils which supported Conifers, Lepidodendra, Cordaites, and Ferns plants which could not have grown in water. Again, with the exception perhaps of some Pinnulariae and Asterophyllites, there is a remarkable absence from the coal measures of any form of properly aquatic vegetation.
These same trunks, when they are placed obliquely or vertically to the planes of stratification, retain their original rounded form, and are uncompressed, the cylinder of bark having been filled with sand, which now affords a cast of the interior. Dr. Hooker inclined to the belief that the Sigillariae may have been cryptogamous, though more highly developed than any flowerless plants now living.
Occasionally some of the calamite brakes and forests of Sigillariae and Coniferae were exposed in the flood season, or sometimes, perhaps, by slight elevatory movements to the denuding action of the river or the sea.
We detected them in the interior of one of the erect Sigillariae before alluded to as of such frequent occurrence in Nova Scotia.
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