FROM THE LOWER COAL-MEASURES. 09 



envelope of parenchyma. Hence the above speculation is not 

 altogether unlikely, since something comparable is to be met with 

 in the Lycopodium referred to. Moreover, in his Memoirs on the 

 Plants of the Coal-Measures Williamson has figured and described* 

 the division of the vascular tissues in several cases, where the pro- 

 cess appears to be in some points similar to that assumed above. 

 Another detail on which a wwd may be said is the structure 

 of the vascular strand of these roots. At the first glance, each 

 bears some resemblance to the corresponding structure ot a 

 monarch root, such as is met with in Lycopodium, Selayinella, 

 Isoetes, and OpJiioylossumf, after a greater or less number of 

 bifurcations, and, according to Williamson, in the rootlets of 

 Stiymaria t From what has been said, however, it is clear that, 

 in spite of this superficial resemblance, we have here to do with 

 a collateral bundle and not with a monarch vascular strand in the 

 usual sense of the words. The case of Stiymaria is of special 

 interest since the vascular bundles of the appendages are derived 

 from a vascular system, which takes the form of a ring of appa- 

 rently collateral bundles. But in Stiymaria the outgoing 

 bundles are derived, in the first instance §, from the apex of the 

 vascular wedges, where they abut upon the pith, while in the 



j 



plant before us they appear to be bundles of the original ring 

 which curve outwards, bodily, into the surrounding tissues. 

 Unless therefore we agree to regard the vascular bundles oi 

 the ring as of the monarch type, we can scarcely apply that 

 term to those met with in the radicular tissues. In this 

 connexion, it may be well to mention that although Williamson 

 regards the vascular strand of the appendages of Stiymaria as 

 monarch, Solms-Laubach seems to consider it as collateral ||. 

 If this view should turn out to be correct, the chief difference 

 between the vascular bundles of Stigmarian appendages and 

 those of the roots of our plant will depend on the mode hi which, 

 according to Williamson, the former are developed. 



Systematic Position. 

 AVhere so many points are doubtful, it is clearly impossible to 

 speak definitely of the systematic position of this plant. 



* < 



■Meas 



t Van Tieghem, loc. cit. 



\ " Stigmaria ficoides," Palatograph ical Bociet/i Publication*, vol. xl 



for 1886. 



§ Williamson, " Stigmaria ficoides," p. 22, note. 



| 'Einleitung in die Palaopbytologie/ p. 281 (Engl. ed. p. 277). 



KUM. JOURN. — BOTANY, VOL. XXTX. * 



