DESCRIPTIVE CATALOGUE 



directly merge into the inner zone of the more solid wood, but 

 are many times separated up by intervening ground-tissue. 



The xylem proper is composed first of bays of normally vertical 

 secondary wood (text-figs. 101, 104, 6.). This is composed of 

 rather irregular but quite normal radial series of secondary 

 tracheids, interspersed with medullary rays (text-fig. 105). 

 The individual tracheids average up to 40-60 p. in diameter, and 

 have a tendency to be wider radially than tangentially. Their 

 walls are generally thinner than those of the perimedullary 

 tracheids. The pitting of the radial walls is bordered-scalari- 

 form, or consists of series of wide, oval, bordered pits (text- 

 fig. 100). A regular icalariform, with apparently a wide border 



Text-fig. 10ft. Cdymbeies Ed ward si, sp. noy. A pair of tracheids showing 

 the bordered Bcalariform pits in the radial walls. No. V. 6127 a. 



and very narrow slit-like perforation, appears to be the 

 commonest type of pitting. 



Alternating with these normal vertical series of secondary 

 tracheids are the horizontally running series (cf. text-figs. 101, 

 107, 108). In transverse section the horizontally running 

 elements show up as dark bands with the low power (text- 

 figs. 107, 108, .r,, .r 2 , etc.), under the high power the pitting 

 of the elongated vessels, which are crossed by radially cut 



