178 KDWATM) C. .TEFFRRV OX 



tired licre, since tlio attached leaves are nhvioiisly sitiiateil in sonic cases iniiiuMliutely 

 above the scars of the Inanchcs, lie aliaiidons that position, and assumes the pi*esence of 

 an intercalated node corresponding to tlie crescentic series of smaller scars on the lower 

 margins of the branch-scars. The writer snggests that tlic crescentic rows of scars of the 

 figure, copied in photograpli (i (PI. 30, fig. 0). really belong to the liasal whorls or oclire- 

 olae of the fallen branches and that as a conse<|uence, so far as can be judged fr(jm exter- 

 nal appearances, the branches of Calamites had the same relation to tiie node as those of 

 Equiseta. The ochreolae of the Calamites were not continuous sheaths as in Eqnisetum 

 but were composed of separate leaves. The ochreolae of the Equiseta not infrequently 

 lack fibrovascnlar bundles and are often obsolete on the upper axial side of the branch. 

 The occurrence of similar features in the Calamites is not improbalile and tlie.se would 

 account for tlie absence of leaf-scars on the upper margin of the branch-scars and for the 

 non-retention of the ochreolar leaves, together witli the normal leaves of the nodes of the 

 parent axis in piiotograpli (i (PI. 30, fig. G). 



But without attaching too much importance to the above explanation, it will l)e well 

 to consider the internal relations of the branches to the nodes, as described in recent works 

 on calamitean anatomy, and, at the same time, to examine the statements as to the nature 

 and disposition of the organs which gave rise to the infranodal tubercles of certain cala- 

 mitean casts. 



In photograph 6 (PL 27, fig. 6), a copy, tlie original of which has been already indi- 

 cated (Williamson and Scott, Phih trans, roy. soc, 1894, B., pi. 78, fig. 11), is a representa- 

 tion of the nodal arrangement of the vascular strands of a Calamite, as seen in tangential 

 section. It will lie observed that these have, generally speaking, the same relation to 

 each other at the node as is exemplified in our piiotograpli 3 (PI. 29, fig. 3) of E. hiemaJe. 

 In the lower ends of the upper medullary rays are situated certain structures which 

 Williamson and Scott [o/j. eit., p. 87G) consider to be leaf-traces. In photographs 4 and 

 5 (PI. 27, figs. 4, 5) , which are taken from Williamson's earlier memoirs (Phil, trans. 

 xoy. soc, 1871, pi. 26, fig. 22; iliid, 1878, pi. 20, fig. 23), these are represented as Jieing 

 the vascular strands of branches. The changed inter[)retatioii of the later memoir need 

 not be considered for tlie i)resent, although, as will be indicated suljsequently, it is of some 

 importance. In the later memoir alrea(l\' referred to, Williamson and Scott (Phil, trans, 

 roy. soc, 1894, B., pi. 78, fig. 11) make the statement that tlie leaf-traces in the Calamites 

 originated from the protoxylem of the bundles of the lower internode, and consequently, 

 it may be assumed, below the nodal -wood, since they inform us that the protoxylem came 

 to an end below the node in Calamites, just as it does in the Equisetaceae. Returning 

 now to the statement that the leaf-traces are found in the upper medullaiy rays and con- 

 sequently above the nodal wood, it may be asked how they have got into this supranodal 



