Page:Proceedings of the Royal Society of London Vol 60.djvu/455

Rh agree. In other respects the differences from any Lepidodendroid fructification are as great as they can be.

I do not doubt that the genus with which Cheirostrobus has most in common is Sphenophyllum. The chief points of agreement are as follows.

1. The superposed foliar whorls. This certainly agrees with the vegetative parts of Sphenophyllum, and, according to Count SolmsLaubach, the superposition holds good for the bracts of the strobili also.*

2. The deeply divided palmatifid sporophylls agreeing with the leaves of various species of SphenoyluS. tenerrimum.

3. The division of the sporophyll into a superior or ventral, and an inferior or dorsal, lobe, agreeing with the arrangement in Bphenophyllum Dawsoni, or S. cuneifolium, according to M. Zeiller’s interpretation.-!-

4. The differentiation of the sporophyll into sterile segments (bracts) and fertile segments (sporangiophores). The comparison with Sphenophyllum is much strengthened if, as I believe to be the case, the segments of the inferior lobe in Cheirostrobus are sterile, and those of the superior lobe fertile.

5. The repeated subdivision of the leaf-trace vascular bundles, in passing through the cortex of the axis,J as in Sphenophyllum Stephanense.

6. The attachment of the sporangia to a laminar expansion at the •distal end of the sporangiophore. As regards this point, comparison should be made with the Bowmanites of Count Solms-Laubach (loc. cit.).

7. The structure of the sporangial wall.

I think that the sum of these characters, to which others might be added, justifies the suggestion that Cheirostrobus may be provisionally placed in the same phylum, or main division, of Pteridophyta, with Sphenophyllum, though indications of possible affinities in other directions are not wanting, and will be discussed on another occasion.

Cheii ostrobus,even more than Sphenophyllum itself, appears to combine Calamarian with Lycopodiaceous characters, and might reasonably be regarded as a highly specialised representative of an ancient group of plants which lay at the common base of these two .series.

It appeal's likely that in Cheirostrobus one of those additional forms

t ^r Etude sur la constitution de l’appareil fructificative des Sphenophyllum.” + Cf. Renault, ‘Cours de Botanique fossile/ vol. 2, PI. 14, fig. 2 ; PI. 15, fi<r. 3 vol. 4, p. 15.
 * Bowmanites Bomeri, cine neue Sphenophylleen Fructification/ 1895, p. 242.
 * Mem. de la Soc. Geol. de France, Paleontologie/ Mem. 11, 1893, p. 37.