Johnson — On Bothrodendron [Cyclostigma) Jciltorkense. 527 

 PLATE XXXVII. 



Fib'- 



1. Bothrodendron kilkor tense. — This is a magnified view of the stem-surface of 



fig. 1, PI. XXXVI. (i). 

 The whorls of leaf-scars stand out well. The bases of the attached leaves 

 are recognizable on the left. 



2. A stem-surface showing projecting (somewhat Halonia-like) leaf-scars (|). 

 8. The stem-surface with depressed leaf-scars (f). 



4. A single leaf-scar with surrounding stem-surface enlarged (^). 



The three scars or cicatricules representing the vascular bundle (central scar) 

 and the parichnos (right and left) are distinctly observable. The sub- 

 circular leaf-scar has a projecting border. On the lower border there is a 

 sear possibly connected with the parichnos-strands. It is a matter of 

 conjecture whether there is a ligular scar or not observable. 



5. Knorria acicularis stage of stem. Natural size. 



6. Branching stem, suggestive somewhat of a drooping habit. Leaf -scars in 



various stages {*). (Geol. Surv. Ireland Collections.) 



PLATE XXXVIII. 



Fig. 



1 and 2 show two stems, at first sight, quite unlike Bothrodendron. 



In fig. 1 the longitudinal fluting is more pronounced than the transverse 



zonation, though this is observable in places (i). (Geol. Surv. Ireland 



Collections.) 

 Fig. 2 shows a markedly calamitoid stem. The longitudinal grooving is 



accompanied by the zonation which coincides with the leaf-scars, and 



suggests nodal diaphragms (J). (Botanical Division, National Museum, 



Dublin.) 



3. A piece of stem-surface in fig. 2 enlarged. The ridges and furrows with 



typical leaf-scars of Bothrodendron axQ evident. The relation of the leaf- 

 scar to the ridge varies, being at one place on it, at another in the 

 groove (^1-). 



4. Knorria Selloi stage of B. Mltorkense, showing the truncated apical ends of 



the leaf-strands, and the fluted surface of the petrification. (Royal College 

 of Science, Dublin, Collections.) 



5. Stem of B. Mltorkense, showing the horizontal zonation, coincident with the 



whorls of leaf-soars. (Trinity College, Dublin, Geological Museum.) 



PLATE XXXIX. 



Fig. 



1. Basal part of the stem of Bothrodendron Mltorkense with surface sculptui-ing 



passing into the Stigmaria ficoides bifurcating rhizome, covered with 



appendage scars (|). (Geological Survey Museum, London. — Number 



26,238.) 



SCIENT. PKOO. R.D.S., VOL. XIII., NO. XXXIV. 4 I 



