204 CONIPEEALB3 [CH: 



assign fossil species to a position within the Coniferales sufficiently 

 definite to be denoted by the use of a name implying close rela- 

 tionship to a particular genus as distinct from a group of allied 

 types. 



Podocarpoxylon. This name^ has been applied to wood agreeing 

 in structure with recent species of Podocarpus and Dacrydium 

 more closely than with other Conifers. As generally understood 

 the genus stands for wood without resin-canals, possessing xylem- 

 parenchyma not necessarily confined to a particular region of 

 the year's growth. In Podocarpoxylon aparenchymatosum Goth, 

 xylem-parenchyma is absent. The bordered pits on the tracheids 

 are in 1 — 2 lows and, if in two series, the pits are opposite or sub- 

 opposite {Podocarpoxylon Schwendae Kub.); rims of Sanio are 

 present. There is no Abietineous pitting in the ray cells ; the 

 pits in the field are typically Podocarpoid, that is there aie few in 

 the field and these appear to be bordered and characterised by 

 an elliptical or linear pore which is oblique or more or less vertical. 

 The medullary-ray pitting next the summer-wood does not aflord 

 a satisfactory means of separating Podocarpoxylon and Cupressino- 

 xylon, but in the region of the spring-elements the Podocarpoid 

 type is a distinguishing feature of Podocarpoxylon, though as 

 stated in the account of recent Conifers the position of the pore 

 is by no means a constant character. On the other hand, the pits 

 in the field may be large and simple as in Sciadopityi, some species 

 of Podocarpus, in Phyllocladoxylon, Xenoxylon and some other 

 genera. 



Phyllocladoxylon. This name was given by Gothan^ to wood 

 similar to Podocarpoxylon but differing chiefly in the occurrence of 

 large, simple pits in the field ['Eiporen'], a feature shared with 

 Sciadopitys and some species of Podocarpus, by Microcachrys, 

 Dacrydium, and Pherosphaera. The tracheids have 1 — 2 rows of 

 bordered pits on the radial waljs, scattered and circular, but not 

 infrequently contiguous and flattened, and if in two rows they may 

 be alternate. There are no clear indications of Sanio's rims in 

 the specimens figured by Gothan and Schenk. There are no resin- 

 canals and no xylem-parenchyma. Phyllocladoxylon agrees closely 

 with Xenoxylon^, but in Phyllocladoxylon the tracheal pits are often 



1 Gothan (0.5) p. 48 ^ j^id. p. 5,5; (10) p. 37. ^ See page 238. 



