XLIV] 



MESEMBRIOXYLON 



209 



Mesembrioxylon Schivendae (Kubart). 



This species is recorded from Attersee in Upper Austria and 

 though probably of Tertiary age it may be derived from Cretaceous 

 strata 1 . Xylem-parenchyma is present ; the bordered pits on the 

 radial walls of the tracheids are in 1 2 rows, usually separate but 

 if contiguous not flattened ; if in 2 rows opposite or sub-opposite ; 

 the medullary rays reach a depth of 13 cells; there are generally 

 1 3 pits (fig. 722, A, B) but occasionally as many as 5 in the field ; 





c. 722. A, B. Mesembrioxylon Schwendae. C, Mesembrioxylon sp. (A, B, after 

 Kubart; C, after Gothan.) 



they are bordered and the pore is obliquely vertical, though this 

 feature is inconstant and in some places the pore is circular or the 

 bordered pit may be replaced by a large simple pit. Sclerous cells 

 occur in the pith. 



Mesembrioxylon aparenchymatosum (Gothan). 



In this Tertiary species, included by Gothan in Podocarpoxylon, 

 from Seymour Island 2 there is no xylem-parenchyma ; the medul- 

 lary-ray cells have 1 2 elliptical-circular pits in the field and the 

 major axis is oblique. The evidence as to affinity is far from con- 

 clusive. 



1 Kubart (II 2 ) PL ra. text-figs. 110. 



2 Gothan (08) p. 8, PL i. figs. 911. 



S. IV 



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