210 CONIFEEALES [CH. 



Mesemhrioxylon sp. (Gothan). 



Gothan^ described some wood as Phyllocladoxylon sp. which 

 he originally stated to have been derived from King Charles Land, 

 but Nathorst pointed out that it came from Scoresby Sound in 

 East Greenland, N. lat. 70° 50'. The pits on the tracheids are in 

 1 — 2 rows, about 16/i high, and smaller than in Xenoxylon; they 

 are scattered or contiguous and flattened, but more often separate ; 

 the medullary rays are composed of a small number of cells and 

 there are 1 — 2 simple pores in the field. 



Mesemhrioxylon antarcticum (Gothan). 



In this Tertiary species from Seymour Island, included by 

 Gothan in Phyllocladoxylon'^, the bordeied tracheal pits are generally 

 uniseriate and separate; the pitting of the medullary-ray cells is 

 like that in Mesemhrioxylon sp. (fig. 722, C). In the account of 

 this wood Gothan points out that the similar pits on the walls of 

 the medullary rays of Sciadopitys are smaller than in the fossil 

 type; in contrast to the tendency towards a vertical elongation 

 of the ray pits in some recent Podocarpineae those of Mesemhrio- 

 xylon are usually more horizontally stretched as in Phyllocladus 

 and some species of Pinus. Gothan compares Cwpressinoxylon 

 Hookeri Arb.^ with Mesemhrioxylon antarcticum, but the former is 

 distingxiished by the smaller pits on the ray cells and by the 

 occurrence of xylem-parenchyma. It is noteworthy that, as 

 Gothan states*, the only recent South American Conifer possessing 

 large simple pits in the medullary-ray cells is Podocarpus andina, 

 while on the other hand there are several Australian genera 

 agreeing closely with the Seymour Island species in the character 

 of the medullary-ray pitting: from this it is concluded that in 

 Tertiary times there was a closer connexion between the South 

 American and Australian regions than at the present day, an 

 inference which, though not improbably correct, rests on slender 

 evidence in this particular case. 



Mesemhrioxylon MUlleri (Schenk). 



This species from Pliocene strata in New South Wales, was 

 described by Schenk ^ as Phyllocladus: the pits on the tracheids 



1 Gothan (OT^) p. 9, fig. 2; (08) p. 6 (footnote). 



2 Ibid. (08) p. 4, PI. I. figs. 4—8. =■ Arber (04). * Gothan (08) p. 25. 

 = Schenk in Schiiuper and Schenk (90) A. p. 873, figs. 424, 425. 



