512 Scientific Proceedings, Royal Dublin Society. 



stone, Tracarta, Cork) is labelled K. Bailyaiia, and sliows what may be called 

 the " Bergeria " stage of B. Jciltorkense. The stem, 1 cm. wide, shows both 

 liorizontal zonation eoiuciding with the wliorls of leaves and the longitudinal 

 grooving. In this specimen the grooving and ridging are not continuous in 

 the vertical direction. If one's attention were limited to this case, one would 

 say that the longitudinal ridges are simply the petrified parichuos-strands. 



Ulodendruid Condition.. (Plate XI;, fig. 3.) 



Bothrodendron kiltorkense presents many illustrations of the puzzling- 

 structures — circular or elliptical depressions on the stem — regarded wlien first 

 seen as distinctive of a genus, Ulodendron, but now recognized as a feature 

 found in many Lepidophytes. The Ulodendron scar is well known in 

 B. inmctatuni, with which tlie small cone of B. mundtim, as described by 

 Watson (21), has been associated. In Lepidodendrou, Sigillaria, and 

 B.punctatum the scars occur in two opposite rows, often in the form of deep 

 pits with an excentric umbilicus. In B. kiltorkense they show no such 

 regularity of arrangement (I have seen one case only of two such scars in a 

 vertical row), being moreover generally so inconspicuous as to have been 

 hitherto overlooked. Heer expressly states that Bothrodendron kiltorkense 

 does not show Ulodendron scars. The general surface of this scar is often 

 much the same in appearance as that of the surrounding stem, except for the 

 umbilicus, which is not markedly excentric, and looks like the scar left by the 

 rupture of a vascular strand. The Ulodendroid field, which may be 1'3 cm. 

 wide, is limited by a slight circular or sub-circular depression, and sometimes 

 shows a similar inner concentric marking, i.e. one of smaller diameter. The 

 whole scar suggests that a structure was attached here by a very narrow 

 vascular base, tliat it was cylindrical in form, and, increasing with age in 

 diameter, pressed with its base against the stem surface. The fact that 

 almost the whole field, except for the point of attachment, may be like that of 

 the surrounding stem-surface supports the view that the Ulodendroid scar in 

 B. kiltorkense represents an appendicular organ with a very narrow point of 

 attachment. 



There is some danger of being misled in the desire to secure uniformity 

 of interpretation of the cause of the Ulodendroid scar. Just as the view that 

 the scar was characteristic of a particular genus was shown to be untenable, 

 so tlie idea that all Ulodendroid scars are of the same nature seems un- 

 warranted. Any appendicular organ of importance must leave a scar which 

 will be more pronounced the deeper-seated the origiu of the organ. Watson 

 seems to me to give (22) an acceptable explanation of the ordinary Ulodeu- 



