. Bulletin of the British Museum (Natural History), Geology. . Fig. 10 Diagrams comparing the venation of sterile and partly fertile pinnules of Matonia braunii. Note that both are often relatively longer. A higher proportion of sterile veins may anastomose. Fertile pinnules are often more fully fertile, relatively narrower and have narrower webs along the rachis. the indusium. In transfers of the more perfect fertile specimens the state of the sori varies, even between adjacent sori. In its most perfect state, however, the sorus is entirely covered by the large convex indusium (Fig. 12). Ofte
. Bulletin of the British Museum (Natural History), Geology. . Fig. 10 Diagrams comparing the venation of sterile and partly fertile pinnules of Matonia braunii. Note that both are often relatively longer. A higher proportion of sterile veins may anastomose. Fertile pinnules are often more fully fertile, relatively narrower and have narrower webs along the rachis. the indusium. In transfers of the more perfect fertile specimens the state of the sori varies, even between adjacent sori. In its most perfect state, however, the sorus is entirely covered by the large convex indusium (Fig. 12). Often this is partly broken in preparation and then the outer parts of sporangia are visible; sometimes only the middle of the indusium remains (Fig. 11). More often both indusium and sporangia have been lost, apparently before the preparation was made, and nothing remains but the projecting placenta (Harris 1961: fig. 38D, named Matonidium); I consider that this loss occurred before preparation because I believe I can distinguish between the bright surface of coal fractured in preparation and the dull surface of coal preserved in contact with mud. Not one Hillhouse specimen showed a sorus of ripe but undischarged sporangia exposed by the loss of the indusium, though sori in this state have been figured from Bavaria and from Greenland. Many Hillhouse sporangia were macerated and proved empty but one from an otherwise empty sorus gave a coherent mass of spores (Fig. 14). The maceration failed to separate them but I. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original British Museum (Natural History). London : BM(NH)
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