4G2 R. KIDSTON AND D. T. GWYNNE-VAUGHAN ON 



are sometimes found in intimate relation with the rhyolites : we will mention two of 

 them that are encountered between Steplitzhof and Illia in descending towards the 

 latter village. The quartzes are generally white or yellowish, and are perfectly compact. 

 Black spots of irregular form are to be noted here and there, generally bordered by an 

 ochraceous band, this colouration being due to iron oxide or to organic matters. There 

 are occasional veinlets in the mass or little ' geodes ' lined by small crystals of perfectly 

 pure and hyaline quartz. The fresh-water quartzes of Illia enclose a great quantity of 

 fossil plant remains. We have found there in abundance the rhizomes of Osmunda 

 Schemnitzensis, Pettko, sp., surrounded by numerous petiole bases. We have also met 

 with stems of Phragmites Ungeri, Stur ; fragments of the leaves of Fagus Deucalionis, 

 Ung., with remarkably clear nervation ; and many pieces of fossil wood belonging to the 

 Dicotyledons. The structure of these woods is unfortunately not sufficiently distinct for 

 their positive determination ; it is possible, however, that they belong to a birch, the 

 leaves of which we have observed. Finally, we have remarked a portion of a cone and 

 fragments of some branches which appear to belong to Sequoia Langsdorffi, Brongt., 

 (sp.). ... In all probability, then, the eruptions of the rhyolites date from the end of 

 the Miocene epoch, or perhaps from the commencement of the Pliocene." 



Description of the Specimens. 



Only two of the specimens actually contained stems. The one figured (fig. 22) was 

 the most perfect and the best preserved, and it contained a single axis. The other 

 included two separate axes, the leaf-coatings of which came into close contact, and it is 

 possible that they represent branches arising from a common stock. 



The diameter of the whole stock may be estimated as about 5 cm. The stem itself 

 is only about 1*1 cm., and consists of a central stele 4 mm. in diameter surrounded by a 

 cortex showing the usual differentiation into an inner thin- walled zone (fig. 22, i. C), 

 *5-7 mm., and an outer sclerotic zone (fig. 22, o. C.) about 3 - 5 mm. thick. The state 

 of preservation of the cortex in the two specimens is very unusual and puzzling. In 

 the specimen figured it is seen that the cellular structure of the thin-walled inner 

 cortex is perfectly clear, while the sclerotic outer cortex shows practically no structure 

 at all. The outer cortex was nevertheless thick-walled, for in the other specimen 

 well-marked fibrous sclerenchyma can be made out in this region, whereas, in this case, 

 it is the thin-walled inner cortex that has completely disappeared. We find it quite 

 impossible to account for this curious freak of preservation. 



Structure of Stele and Leaf-track. 



The xylem ring consists of seventeen to eighteen separate strands, typically 

 Osmundaceous in form and appearance (fig. 28), surrounding a pith of fairly thick- 

 walled parenchymatous cells that increase in size towards the centre. There is no 



