202 CONIFBRALBS [CH. 



assigns to Taxodioxylon two specimens from Tertiary strata m 

 Spitzbergen and it is probable that the wood may belong to plants 

 which bore the twigs described by authors as Taxodium distichum 

 and Sequoia Langsdorfii. 



The name Taxodioxylon is retained as a section of Cwpressino- 

 xylon and not as a separate genus on the ground that the characters 

 on which it is based do not appear to be sufEciently distinctive or 

 constant to warrant its recognition as a well-defined generic type. 



III. TAXOXYLON. Unger. 



Unger^ gave this name to fossil wood characterised by the 

 presence of spiral bands in the secondary tracheids, a feature 

 especially associated with the recent genera Taxus, Torreya, and 

 Cephalotaxus, but by no means unknown in other Conifers^. The 

 name, in the form Taxoxylum, was substituted for Taxites em- 

 ployed by Goeppert^ for some species of Tertiary wood. Apart 

 from the presence of spiral bands Taxoxyhn agrees with Cwpres- 

 sinoxylon, though according to Lignier the medullary rays are 

 deeper in the latter genus. 



Taxoxyhn scalariforme (Goeppert). 



This Tertiary species, originally described by Goeppert from 

 Hungary as Taxites scalariformis , was renamed by Unger Taxoxylum 

 Goepperti. According to Schenk* it is the only species among 

 those recorded by Goeppert which should be retained in Taxoxyhn, 

 the spiral pattern of the tracheids being due to the presence of true 

 bands and not, as in the other species, the result of enzyme action 

 on the wood which produces a spiral striation closely simulating 

 spiral bands. The bordered pits on the tracheids are circular and 

 separate ; the medullary rays are uniseriate and from 1 to 10 cells 

 in depth ; there are no resin-canals. 



Goeppert's species Taxites Ayckii (after Herr Aycke) of Ter- 

 tiary age was retained by Kraus^ as an example of that genus but 

 afterwards transferred to Cwpressinoxyhn on the ground of the 

 absence of true spiral bands in the tracheids. Lingelsheim® also 



1 Unger (47) p. 33. 2 ggg p^ge 134. 



= Goeppert (40). ■> Schimper and Schenk (90) A. p. 859. 



' Goeppert (40) p. 188; (50) p. 244; Kraus (64) p. 197. 



« Lingelsheim (08) p. 27. 



