214 PROF. WILLIAMSON ON THE FOSSIL PLANTS OF THE COAL-MEASURES. 
Plate 
Fig. 
Pages on -wliicli 
references are 
made to the 
figures. 
8 
27 
Condition of the parenchyma occupying the areas, e, 
of fig. 25. 
200 
8 
28 
Transverse section of a stem or petiole of Paichiopteris 
wcequalis, Will. : a, lai’ge tracheids, occupying one 
side only of the vascular bundle; h, much smaller 
tracheids, occupying the opposite side of the vascular 
bundle, a ; c, c', small tracheids, similar to h, occu- 
})ying the two extremities of the section of the 
vascular bundle; d, a cluster of small tracheids, 
apparently detached from c, probably destined to 
supply some lateral appendage not seen in the 
section . .. 
206 
