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 stated, it had previously been well known elsewhere. I regard these plants, so well described by Williamson, as true Calamites, in the sense in which that word is used above.

(2) The same palaeobotanist has independently expressed the belief above stated, that the leaves of Calamites are distinct from those of Asterophyllites, and has also stated a distinction between those so- called Volkmannioe which may be regarded as fruits of Calamites and those which belonged to Asterophyllites *. He has also described a specimen of Stigmaria showing the medullary rays, and otherwise approaching to the structures which should be found in the roots of the typical Sigillarioe above described.

(3) Schimper, in his ' Paleontologie Vegetale,' vol. xi., has treated the Sigillarioe very slightly. He adds no new facts of importance to their history, does not separate them from the plants of the genus Lepidophloios, usually mixed with them, refers the whole to one genus, and places them with the Lycopodiaceae.

(4) Binney, in the Palaeontographical Society's Publications, vol. xxiv., has described, under the name of Bowmanites cambrensis, a very interesting plant, which I regard as a typical member of the group Asterophyllites, as distinguished from Calamiteoe.

(5) Attention having been directed by Prof. Huxley to the presence of spore-cases in Coal, I have endeavoured to show, in a paper in the ' American Journal of Science ' for April, that these bodies are not a large constituent of ordinary Coal, and that any importance which they possess in this respect is due to their identity in chemical composition with those cortical and epidermal tissues which, like the suberin of cork, are more nearly allied in composition to Coal than any other recent vegetable matters, and better fitted, by their chemical and mechanical properties, for its production.

EXPLANATION OF THE PLATES.

Plate VII.

Fig. 1. Sternbergia, pith of Dadoxylon; 1 a, section of one side, showing diaphragms ; 1 b, section of a diaphragm and three wood-cells, magnified ; 1 c, two wood-cells, highly magnified, showing reticulated walls.

2. Sternbergia, pith of Sigillaria, natural size ; 2 a, 2 b, discigerous tissue investing the same.

3. Sternbergia, pith of Sigillaria, natural size ; 3 a, discigerous and scalariform tissue.

4. Sternbergia, natural size ; 4 a, reticulato-scalariform tissue.

5. Sternbergia, natural size ; 5 a, 5 b, scalariform and reticulato-scalariform tissue.

6. Scalariform vessel of Lepidophloios.

Plate VIII.

Fig. 7. Sternbergia, of Lepidodendroid tree ?, natural size ; 7 a, scalariform tissue.

8. Section of a flattened stem (Sigillaria?) 1 foot in diameter, converted into coal, with Sternbergia-pith.


 * Manchester Lit. and Phil. Soc. Proceedings, Feb. 1871.