XXXIII] CORDAITES 223 



structure of the vascular bundles with Cycads than with Conifers 

 though there are points of contact with both of these classes. 

 The roots branch freely and their horizontally extended arms 

 (figs. 468, A; 478) suggest growth in swampy ground; anatomi- 

 cally they conform to the recent Gymnospermous type and there 

 is good evidence that in some cases fungal mycelia lived symbio- 

 tically in the cortex of coralline rootlets. 



Sternberg 1 figured some leaves of Cordaites from Carboniferous 

 rocks in Bohemia under the generic name Flabellaria in the belief 

 that they belonged to a Palm. Brongniart substituted a new 

 name Pycnophyllum 2 on the ground that Corda had disproved 

 the supposed relationship with Monocotyledons. The name 

 Cordaites was instituted by Unger 3 , his definition being based on 

 leaf-form as well as on stem-anatomy. It has recently been 

 proposed to revive the forgotten designation Pycnophyllum*, but 

 the reasons given are hardly likely to induce botanists to discard 

 the familiar generic name which perpetuates the memory of 

 Corda. As already pointed out, the name Cordaites, even though 

 employed in what has always been regarded a legitimate sense, 

 is no doubt often given to specimens of some other allied member 

 of the Cordaitales which can only be recognised as such in the 

 case of more completely preserved material. The naming of 

 wood of the Cordaitean type, but which may equally well belong 

 to another genus, raises a difficult question : if there is satisfactory 

 evidence from collateral sources that the wood is that of a 

 Cordaites Grand'Eury's name Cordaixylon 5 or Schenk's form 

 Cordaioxylon 6 may be used, though there seems to be no adequate 

 reason against the use of the name Cordaites. If there is no con- 

 firmatory evidence available and it is impossible to say whether 

 the wood is that of a Conifer or a Cordaites, or some other plant 

 with the same type of secondary xylem, Endlicher's term Dado- 

 xylon 7 is most conveniently employed. The confusion liable to 

 follow from the use of the two generic names Dadoxylon and 



1 Sternberg (23) A. PL xvin. 2 Brongniart (49) A. p. 65. 



3 Unger (50) A. p. 277. 4 Tuzson (09) p. 18. 



5 Grand'Eury (77) A. p. 257. 



6 Schenk in Schimper and Schenk (90) A. p. 243. 



7 Endlicher (47) p. 298. 



