24 



FOSSIL PLANTS. 



allied to the latter genus, found lying around my specimens, pointed out the probability of 

 such being the case, when they first came before me ; but it was only when the structure 

 of their central axis was examined and found to be of the same character as the stem of 

 Calamodendron that the connection of the one with the other was clearly established. 



Plate IV, fig. 1, represents a transverse section of Specimen No. 5, one of the cones, 

 ,5th of an inch in diameter, magnified forty-five times. It shows the central axis of the 

 column, composed of hexagonal and pentagonal tubes, which have been somewhat 

 displaced from their original position. Around the part last described is a space where 

 the structure is not shown ; and then comes a six-sided girdle of rather larger tubes, 

 giving rise to bundles of pseudo-vascular tubes (enveloped in cellular tissue), which 

 constitute the thick portion of the disc-like scale, which divides the cone into receptacles, 

 or cells, containing the sporangia, and from which the leaves proceed and go upwards. 

 These sporangia (marked j^'j?) are of an irregular oval shape, having the broader ends near 

 the periphery and the narrower next the central axis. They were arranged in series of 

 fours, around a stout spike, as described by Ludwig. In this transverse section, of course, 

 only two are shown, and they appear to have been enveloped in a bladder-shaped 

 bag, traces of which are seen in the dark curved lines (marked kk) bounding the four 

 best preserved sporangia, shown in the lowest part of the figure, and which, when in a 

 perfect state, would in a transverse section have presented a cordate form. 



In this specimen distinct evidence of six of these bags, each containing twelve 

 sporangia, is shown instead of the five containing ten sporangia in Ludwig's figure. The 

 outer coating of the sporangium is composed of a single row of cells, and the sporangium 

 itself is full of round bodies, like microscopic spores, some of which have an appearance 

 of a triradiate ridge on their outsides, but the majority appear plain, as represented in 

 the figure. The section seems to have been made across the cone midway betwixt the 

 base of the scale forming the cell-partition, and the spike or spine supporting the 

 sporangia, and therefore affords little evidence of the structure of either of those parts 

 of the cone. Por this we must resort to the longitudinal sections contained in Plate V, 

 which will afford us the requisite information. 



\ 5. The Specimen (Cone of Calamodendron commune) No. 6. 



(Plate 4, fig. 2.) 



Plate IV, fig. 2, represents a transverse section of No. 6, (^^th of an inch in diameter, 

 magnified 54 times), another cone, similar to that last described. This has the walls of 

 its sporangia considerably disarranged, and only a few spore-like bodies are scattered 

 about the section. The central axis is in a fair state of preservation, and is composed of 

 a mass of hexagonal and pentagonal tubes, smaller in size than those shown in fig. 1, 

 but like them in other respects. A space without structure then intervenes between the 



