PLATE I. 



Calamodendron commune. 



Fig. 1 (No. ]). A decorticated specimen from the Upper Brooksbottom Seam of 

 Coal, Lancashire. Natural size. 



Fig. 2 (No. 2). The furrowed and ribbed cast of the central axis of a large 

 specimen from the same locality as No. 1. Natural size. 



In tlie following Plates the same parts in the specimens figured are indicated by the same letters, as 

 follow : 



a a. The middle part, showing the central axis, or pith, composed of large hexagonal utricles. 



b b. The pseudo-vascular cylinder, composed of quadrangular tubes, having all their sides perforated 

 by oval openings ; they are arranged in wedge-like bundles and in radiating series, originating from 

 " orifices " near the thin end of the wedge next the central axis, increasing in size as they approach the 

 circumference, and divided by medullary (?) bundles. 



c c. Wedge-shaped masses of lax tissue, composed of oblong cells, in radiating series, having the thick 

 end of the wedge next the central axis. Both wedges and ceils increase in size in the opposite direction 

 to that seen in the tubes and masses of the pseudo-vascular cylinder, b b. 



d. Diaphragm, apparently composed of cellular tissue, dividing the central axis or pith horizontally 

 at the Joints. 



e e. Oval-shaped bundles of pseudo-vascular tissue, passing from the central axis, or pith, and com- 

 municating with the Leaves. 



ff. Bundles of cellular tissue, of an elongated oval form, near the circumference of the stem, 

 dividing the pseudo-vascular cylinder, and having the appearance of medullary bundles, though only ex- 

 tensions of the wedge-shaped masses, c c. 



ff g. The central axis or column of a Cone. 



h h. The Scales or Leaves forming the divisions of the Sporangium-receptacles or cells of a Cone. 

 a. The Sporangium-bearers of a Cone. 



Sporangia full of Spore-like bodies. 

 kk. Portions of the bag containing the Sporangia. 



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