344 : -PROCEEDINGS OF SOCIETIES. 
s' 
which latter had been 27 inches in circumference. ence these plants, 
of 
organisation. On the other hand, the Lepidodendra and Sigillaria 
of the Coal Measures had stems rising like 
the mast 
i These da diff 
from that which sufficed for the dwarfed living representatives of these 
forest trees, and such an organisation was provided for them. The 
lecturer then traced the processes of growth by which young twigs, 
‘th a @ : 2" - 
central vascular bundle of the young twig, and an outer one fo 
of exogenous layers. Of these two cylinders the latter alone entered 
the roots, and the former the leaf-clad twigs ; hence the sap absorbed 
a group of which the organisation of both stems and fruits are alto- 
gether distinct from that of Calamites. The Professor next reviewed 
various forms of the stems and leaf-stalks of Ferns, some of which he 
had succeeded in connecting with the leaves to which they belonged ; 
groups of Cryptogams and Gymnospermous Exogens. The question 
arises, Were there in that age no representatives of the Dicotyledo- 
nous and Monocotyledonous plants—that is, plants of the ordinary 
