Manchester Memoirs, Vol. hit. (191 3), ^0. 18. 7 



tracheids nearer the outside are pitted. There seem also 

 to be transition stages between the two. In some of the 

 outermost scalariform tracheids the pits are wide and 

 oblong {PI. II., Fig. 8rt), and in some of the next tracheids, 

 which have two rows of pits, one notices here and there 

 cases of "fusing" of two lateral pits(P/. 11, Fig. Sd), both 

 of which cases have been recorded for the Araucarineae 

 by Boyd Thompson.'' Where the rows of pits occur 

 they are usually alternate, and being somewhat crowded 

 become slightly polygonal in shape. {P/. II., Fig. Sc.) The 

 outermost tracheids have usually only one row of pits. 

 (Pi. 11, Fig. Sd.) The state of preservation is not 

 sufficiently good to show in the longitudinal sections the 

 nature of the outer pore of the bordered pit. But that the 

 pits were bordered can be inferred from certain of the trans- 

 verse sections where a distinct lens-shaped thickening of 

 the radial walls is recognisable, and in one or two cases 

 traces of the middle lamella were observed. The compara- 

 tive sizes of tracheids and pits are as follows : .Scalariform 

 tracheids, '02 to '025 mm. ; pitted tracheids, -025 mm., some- 

 what narrower in the tangential diameter. Where one row 

 of pits occur, the latter are slightly flattened above and 

 below by the adjacent pits, and have a horizontal diameter 

 of '017 mm. and a vertical diameter of -015 mm. Where 

 two rows of pits occur, each has a horizontal diameter 

 of about "012 mm. and a vertical diameter of 01 mm. 



The medullary rays are numerous. The)' are generally 

 one cell in thickness, and vary in height from one to about 

 six rows of cells. It is impossible from the state of 

 preservation to say whether there are any ray tracheids or 

 not. The cells of the medullary ray, as far as one can 

 tell, are all of one kind. They are horizontally drawn out 

 so as to be in contact with about five or six tracheids. 



" Thompson, R. B. "Anatomy and Affinities of the Arancarineae" 

 FML Trans., vol. 204, 191 3, p. 18. 



