320 



DESCRIPTIVE CATALOGUE 



abrupt change the large-celled pith merges in the pf-riinedullani 

 zone, in which the ground-tissue cells are smaller and there are no 

 gum-canals. This zone is specially characterised by the loosely 

 arranged, anastomosing bands and groups of xylem-elements 

 (text-figs. 101, 103, 109, pm.). 



The pcrimedullary xyleni consists of clusters or small groups 

 of tracheids, and short radially running series of tracheids 



pm 



text-fig. 104. Colymbetes Edwardsi, sp. nor. Transverse section showing 

 clearly the bays of the first vertically running wood-ring, h., and the 

 steady alternation of vertically and horizontally running wood-riugs. 

 This should be compared with text-fig. 107, where the bands are 

 more broken up by outgoing leaf-traces! />., pith ; pm., perimedullary 

 wood-zone. X 2. No. V. 6132 a. 



