18 



FOSSIL PLANTS. 



structures, I noticed numerous small cones lying detached around them in the stone. 

 These I immediately recognised as resembling Volkmannia, and showed them to Dr. 

 J. D. Hooker, F.R.S., who also thought that they bore great resemblance to that genus of 

 fossil plants. On further examination, from the structure of the central axis of the cone 

 being the same as that of the stem of Calamudetidron, it was evident to me that the cone 

 was the fructification of that plant. This was before Dr. Ludwig's paper came under 

 my notice. 



My specimens of the organs of fructification will be described at length, as they show 

 structure in all their parts, and exhibit the spores in the sporangia, which Dr. Ludwig's 

 do not, so far at least as described by that author. 



The cone is one third of an inch long in my best specimens, although it may have 

 exceeded that length. In one case there are eight sporangium-receptacles, placed one 

 immediately above the other. These receptacles are of a crown-shape, formed by the 

 scales which proceed from the central axis of the cone, at first at right angles, and then, 

 when they reach the outside, taking a vertical direction, somewhat like the scales of 

 Lepidostrobus, figured and described by Dr. Hooker^ ; but they are arranged one above 

 another throughout the whole series, and not in a spiral direction. The sporangia are 

 of an irregular egg-shape, slightly elongated, and are arranged in fours, symmetrically, 

 around a thorn-like process or spindle coming from the axis ; but I have not been able 

 in my specimens to see them distinctly enveloped in a bladder-shaped bag so plainly 

 as described by Ludwig : but there is clear evidence of such a covering. In each 

 receptacle there are six of these series of four, arranged radially with regard to the 

 central axis ; so there are twenty-four sporangia altogether in every receptacle. Each 

 sporangium has a covering composed of a single row of parallel cells, which generally 

 shows evidence of some disturbance, so that the original form of the sporangium is not 

 often well displayed. This is filled with numerous round spore-Hke bodies, some of 

 them having apparently a tri-radiate appearance, and looking as if they had divided 

 into three sporules. These are not unlike similar spores seen in Lepidostrohus Browni ; 

 but are more transparent, not so dark in colour, and of smaller size. 



The attachment of the bladder-shaped bag, containing the four sporangia, to the 

 spindle is not well seen ; but the connection of the latter to the central axis of the 

 cone is clearly shown, and is exactly the same as that described by Dr. Ludwig in his 

 specimen. 



The outside of the central axis is composed of tubes of hexagonal and pentagonal 

 forms, having all their sides marked by transverse openings of an elongated oval shape, 

 similar to what are observed on the pseudo-vascular bundles of tubes of Calamodendron ; 

 but blank spaces show that some portions of the axis have been of a more perishable 

 nature. 



^ ' Mem. Geo). Surv. Great Britain,' vol. ii, part 1, p. 449, plate 7, fig. 8. 



