CHAPTER XXXIII. 



CORD AIT ALES. 



A. POROXYLEAE. 



Poroxylon. Renault. 



In 1879 Renault 1 briefly summarised the anatomical features 

 of some silicified vegetative shoots from the Permian of Autun 

 for which he instituted a new family, the Poroxyleae. The more 

 complete account contains a description of two species, Poroxylon 

 Boysseti and P. Duchartrei : the latter was afterwards recognised 

 as a stem of Heterangium. Renault considered this new genus 

 to be closely allied to Sigillaria and Sigillariopsis and pointed 

 out its resemblance to Cordaites. Additional species have since 

 been described but as yet the genus has not been found outside 

 France in Permo-Carboniferous strata of Autun and the St Etienne 

 district. The results of a more detailed investigation of the 

 anatomy of the genus were published by Bertrand and Renault 

 in 1882 and since then 2 Bertrand, Renault, and Scott have added 

 to our knowledge of this interesting type. In several respects 

 Poroxylon stems present a striking resemblance to Lyginopteris, 

 but the recent discovery of the genus Mesoxylon has given greater 

 significance to the characters in which Poroxylon agrees with 

 representatives of the Cordaitales. Our knowledge of the genus, 

 though exceptionally full with regard to the anatomy of vegetative 

 shoots, does not include any precise information as to the repro- 

 ductive organs. 



1 Renault (79) B. p. 272, Pis. xm. xiv. 



2 Bertrand and Renault (82); Bertrand, C. E. (89); Renault (96) A. p. 279, 

 (93) A. Pis. LXXIV. LXXV; Scott (09) B. p. 500. See also Scott and Maslen (10) 

 Maslen (11) p. 409. 



