436 STUDIES IN FOSSIL BOTANY 



and above this level no more bundles were received (see 

 Fig. 1 64, C). The petiole, where it first detaches itself 



•^SM 



Fig. 167. — Meduilosa'augHca. A. Transverse section of petiole, showing the numerous 

 vascular bundles, v.b ; ?n.c, mucilage-canals ; hy, hypoderma, with sclerenchymatous 

 ribs. The whole has the structure of " Myelo.xylon Laiidrioiii." x about S. S. 

 Coll. 636. (G. T. G.) B. Vertical section of leaflet, v.b, vascular bundles of mid- 

 rib, and lamina ; jj/.c, mucilage-canal. Palisade-tissue shown towards upper surface. 

 x 28. Phil. Trans, S. S. Coll. 691. 



from the stem, has the following structure (Fig. 167, 

 A) : On the extreme outside we may find a layer or two 

 of palisade-like tissue (rarely preserved), which probably 

 served for assimilation. Within this is the broad hypo- 



