516 Scientific Proceedings, Royal Duhlin Society. 



appears as a depression, and the apical slope is inclined upwards from the 

 upper edge of the depression. This flap-like ledge beyond the upper limit 

 proper of the leaf-scar I have found a very reliable guide in ascertaining 

 which is the upper end of isolated pieces of stem (Plate XXXVII, figs. 

 2 and 3). 



The specimen illustrated (Plate XXXVI, fig. 2) from Kiltorcan is 

 strikingly like the one from Bear Island described by Kathorst, and regarded 

 by him as rhizomatous. It is a piece of bifurcating stem in wliich the 

 dichotomy is not absolute, as the branch seen to the right is thinner, and 

 the left one shows an overtopping tendency. Its more distant leaf-sears are 

 in spiral or oblique whorls, i.e. parastichies, not in horizontal, " alternating " 

 whorls, as in the left branch. Further, the longitudinal striation observable 

 in the parent stem is continued into the left branch, but is almost absent 

 from the right one. The right-hand branch runs as a core through the stone, 

 so that at its broken end one can see apparent suggestions of a central 

 axial strand of tissue of unrecognizable nature, and also the lower surface 

 (seen from within) of the cortex of the branch. 



Another argument used by Nathorst against the Stigmarian connection is 

 the rarity of Stigmaria in the Bear Island deposits compared with the 

 frequency of Bothrodendron remains. Most of the Stigmarias were collected 

 in 1868, when the botanical importance of the beds could not be fully realized 

 by the explorers. Nathorst, in 1898, got one or two specimens only, and 

 Andersson, in 1899, none at all. Now, Nathorst twice mentions that his visit 

 to the Bothrodendron locality was compulsorily short, and that Andersson's 

 specimens of Bothrodendron were nearly all pieces of young stems. The 

 absence of Stigmaria in the later collections is tlius explicable. Stigmaria 

 represents the basal part of a whole plant, and is naturally less frequently 

 met with than the numerous aerial branches. It is worth recalling here that 

 Baily assigns a Stigmaria-stage, in his plan of restoration, to Knorria Bailyana 

 without giving his reasons for the association. In my examination of the 

 Museum material I had seen evidence indicating the organic connection of 

 Stigmaria with Bothrodendron, and kept a look-out for further proof in the 

 quarry work I did at Kiltorcan. I have now several specimens in which the 

 same fossil shows clearly at one end the true Stigmaria scars, and at the other 

 end, in continuous connection with the Stigmaria, a stem impression which 

 shows the usual surface-markings and some scattered leaf-scars of Bothro- 

 dendron. These specimens show that Bothrodendron has a normal under- 

 ground Stigmaria-stage. During the week's work we got innumerable 

 pieces of stem, but only a few specimens of Stigmaria, and at one particular 

 part of the quarry. In keeping with this, too, we found only one or two 



