CALAMARIEAE. 315 



beautiful and well-pronounced form as rosettes of striated protuberances 

 on the mould-plates of certain large stems of Calamitae with short members, 

 for example in Calamites multiramis l ; these .plates undoubtedly represent 

 the outer surface of the ring of wood, which is partly preserved in the form 

 of a thin coating of coal. The varied and peculiar arrangement of the scars 

 of the branches on the nodes, for example in the group known as Calami- 

 tinae, will be noticed again below. Certain anomalies in the sculpture, such 

 as occur here and there on the internodes, but from which no conclusions 

 can be drawn, will be found figured and described in Weiss 2 . 



Now that the casts of Calamitae which are produced by the filling up 

 of the medullary cavity have been thus fully considered, it remains only to 

 add a few words concerning the specimens which represent the outer surface 

 of the stem. This surface, which in ordinary Calamitae is only preserved 

 in a rind of coal, is either quite smooth or is folded in slight wrinkles ; the 

 nodes are indistinct, and are perhaps marked only by the presence of any 

 flat patelliform branch-traces that are present. No leaves are seen ; either 

 there were none, or they dropped off early, or were simply not preserved. 

 Probably the latter supposition comes nearest to the truth, for since specimens 

 of some aberrant forms of Calamitae, the Calamitinae and Archaeocalamites 

 radiatus, have actually, though rarely, been found bearing leaves, we must 

 ultimately assume that the rest of the group were furnished with leaves. We 

 shall have something more to say about these remains of leafy stems further 

 on, when describing the groups to which they belong. 



A classification of the Calamitae is a difficult task. It is exactly in the 

 casts that the characteristic marks are so sparingly preserved to us ; and if 

 we must be content consciously to have recourse to an artificial arrange- 

 ment, as best fitted to give a clear view of the whole, the one framed by 

 Weiss 3 is recommended by its simplicity and convenience, and by the 

 circumstance that it nowhere oversteps the frame supplied by the remains 

 of stems. Weiss has himself described with clearness the objects which he 

 had in view in his divisions, and the importance which he attaches to them. 

 He says 4 distinctly : ' A grouping of Calamitae without regard to their 

 appendicular organs, especially the organs of fructification, is only a more 

 or less elegant mode of getting them arranged in some order, a mechanical 

 procedure for practical convenience,' and in another place : ' If we neverthe- 

 less propose to group the Calamitae according to sterile bits of stems, and 

 not even to employ their elementary structure as a principle of division, the 

 only value of such a classification would be to make it more easy to get a 

 general view of the whole from certain interesting points.' Such points are 

 especially the distribution and position of the branches ; and if Stur 5 refuses 



1 Weiss (5), t. 10, f. 2, and t. 12. 2 Weiss (5), t. 17, f. 4, and p. 135, with figure. 



3 Weiss (5). * Weiss (5), p. 139. 5 Stur (5), p. 164. 



