212 CONIFERALES [CH. 



It has been suggested by Gothan^ that this species should be 

 referred to Podocarpoxylon : the pitting of the medullary-ray cells, 

 though seldom preserved, seems to differ from the typical Cwpress- 

 inoxylon form. It is therefore referred though with some hesitation 

 to Mesembrioxylon. 



V. PARACEDROXYLON. Sinnott. 



Paracedroxylon scituatense Sinnott. The generic name Para- 

 cedroxylon^ was instituted for this Cretaceous species from Scituate, 

 Massachusetts, in order to indicate its resemblance to Cedroxylon 

 as defined by Kraus, more especially as regards the pitting of the 

 tracheids and the absence of resin-canals and xylem-parenchyma 

 in the normal wood, and to show that in some features it differs 

 from that genus, namely in the absence of Sanio's rims and in 

 the smooth and thin unpitted horizontal walls of the medullary-ray 

 cells. In typical species of Cedroxylon xylem-parenchyma is 

 present and the tracheal pitting alone is not a distinguishing 

 feature. The annual rings are broad and not well defined ; resini- 

 ferous parenchyma is restricted to wounded regions. Groups of 

 thin-walled cells, which it is suggested may be abortive resin- 

 canals, though there is no evidence that this is the case, and thick- 

 walled parenchyma occur in the wounded tissue. The tracheids 

 have a single row of bordered pits, generally circular. The medul- 

 lary rays, 2 — 12 or more cells in depth, are pitted only on the radial 

 walls and there are 4 — 6 circular pits with an oblique slit-like pore 

 in the field. The occurrence of bands of much thickened and 

 pitted parenchyma is regarded as evidence of wounding : canal-like 

 spaces occur in the traumatic tissue. Moreover in the affected 

 regions the medullary-ray cells often show pitting on their hori- 

 zontal and tangential walls. 



Sinnott regards the absence of Sanio's rims as indica,tive of 

 Araucarian affinity while the traumatic phenomena are interpreted 

 as Abietineous characters. The genus rests on a slender basis: 

 except for the absence of xylem-parenchyma the normal wood 

 differs verj^ slightly from Cicpressinoxylon and it is not distinguished 

 by any well-marked features from Mesembrioxylon. 



Jeffrey^ has described the axis of a Geinitzia cone from the 



1 Gothan (08) p. 7. - Sinnott (09). ^ Jeffrey (11). 



