270 



On the Catamites of the Coal-measures. [Jan. 26, 



bifurcate, like the wedges with which they are associated, and are con- 

 tinuously prolonged from internode to internode. 



The ordinary structureless fossils found in shales and sandstones receive 

 a definite interpretation from the specimens described. The fistular me- 

 dullary cavities due in the first instance, not to decay of the tissues, but to 

 the rapid growth of the stem, became further enlarged by the entire absorp- 

 tion of the true pith, which commenced after the latter had fulfilled 

 its purpose in the origination of the woody wedges. This process ter- 

 minated at an undulating line of arrested absorption, the convexities of 

 which projected outwards, opposite the primary medullary rays, and in- 

 wards, opposite the woody wedges ; and the inorganic cast of the cavity thus 

 formed by a physiological action constitutes the Catamites commonly seen 

 in collections. Hence they are not, like the Sternbergise, casts of a cavity 

 within a true pith, but their form represents that of the exterior of the 

 medullary tissue. The ridges and furrows of these internal casts are not 

 identical in position with the similar undulations of the exterior of the 

 woody zone, but alternate with them ; so that the ligneous cylinder pro- 

 jects both externally and internally where the woody wedges are located, 

 and contracts, in like manner, at the intermediate points opposite to the 

 primary medullary rays. The thin carbonaceous film which frequently 

 invests these casts is the residue of the altered elements of the woody 

 zone, and possibly also of the bark, which latter has been very liable to 

 become detached from the former. The surface-markings of this carbo- 

 naceous film have usually no structural significance, being merely occasioned 

 by the impression of the hardened casts which they invest. 



Two kinds of branches are given off by Catamites, — the one subterranean, 

 springing from peculiarly formed rhizomes, and the other aerial, attached 

 to the upright unbranched stems. The former of these are of compara- 

 tively large size, the nodes from which they have been detached being 

 marked by large concave lenticular scars as phragmata. These branches 

 appear to have been given off from central rhizomes in accordance with a 

 regular phyllotaxis, but which varied in different species. The aerial 

 branches, on the other hand, were merely slender appendages to a virtually 

 unbranched stem ; they were arranged in verticils round the nodes, in 

 variable numbers. Each branch sprang from the interior of one of the 

 woody wedges, the two halves of which were forced asunder to admit the 

 base of the appendage, and from which its constituent vessels were derived. 

 The branch, deprived of its bark, never appears to have had a diameter 

 equal that of two of the woody wedges, and the rarity of their occurrence 

 attached to the stem seems to indicate that they were deciduous. The bark 

 investing them is not yet known, and the exact nature of the foliage which 

 they bore is also uncertain, owing to discordant testimony respecting it ; 

 but there appears no reason for doubting that some of the verticillate 

 Asterophyllites or Annulariae represent it, though there is uncertainty 

 respecting the actual forms to be identified with Catamites. The roots 



