Page:Proceedings of the Royal Society of London Vol 60.djvu/453

Rh the peduncle above described, except for the absence of any secondary tissues. The wood has twelve prominent angles, at which the spiral trachere are situated, so its development was, no doubt, centripetal. The inner trachea? have pitted walls, and are intermixed with scattered parenchymatous cells, imperfectly preserved. The phloem has entirely perished.

The most interesting anatomical feature is the course of the leaftrace bundles, which can be followed with the greatest exactness on comparing sections in the three directions.

A single vascular bundle starts from each angle of the stele for each sporophyll, and passes obliquely upwards. When less than half way through the cortex, the trace divides into three bundles, one median and two lateral. The lateral strands are not always both given off exactly at the same point. A little further out, the median bundle divides into two, which in this case lie in the same radial plane, so that one is anterior, and the other posterior. The median posterior bundle is the larger, and before leaving the cortex this, in its turn, divides into three. There are now six branches of the original leaf-trace, three anterior, and three posterior, which respectively supply the lower and upper lobes of the sporophyll. The three segments of the lower lobe are supplied by the twro lateral bundles first given off, and by the anterior median bundle, while the upper segments receive the posterior median bundle and its two lateral branches. In the base of the sporophyll, all six bundles can be clearly seen, in tangential sections of the cone, three above and three below. As the segments become free, one bundle passes into each, and runs right through the pedicel to the lamina. In the fertile lamina the bundle subdivides, a branch diverging to the point of insertion of each sporangium.

One of the longitudinal sections passes through the base of the cone, so as to show part of the peduncle in connection with it. In this peduncle secondary wood is present, just as in the separate specimen belonging to the Williamson collection. Higher up in the axis of the cone, where the sporophylls begin to appear, the secondary wood dies out. This evidence materially confirms the conclusion that the Williamson peduncle really belongs to our strobilus.

It is evidently necessary to establish a new genus for the reception of this fossi l ; the generic name which I propose is Cheirostrobus, intended to suggest the palmate division of the sporophyll-lobes ixeiPi hand). The species maybe appropriately named Pettycurensis, from the locality where the important deposit occurs, which has yielded this strobilus and so many other valuable specimens of