Specimens of Fossil Wood. 243 



The tangential section shows numerous medullary rays, 

 simple or with one series of cells superimposed, and very 

 variable in length, from one cell to many in each. 



This structure is as near to that of JDadoxylon Clarkii. 

 as could be expected in the more slender stems or branches 

 represented by these specimens. The cortical tissues are 

 absent. The pith does not show Sternbergia structure, ex- 

 cept very faintly in parts. 



The specimens from the Naples beds are imperfectly pre- 

 sented, but in so far as can be determined, may belong to 

 the same species. 



I have already pointed out, in the publications above re- 

 ferred to, that the characters of this species approximate to 

 those of the stems of Cordaites, so that it may be referred to 

 Cordaioxylon rather than to Badoxylon proper. I may now 

 add that the species is very near to Araucarites Ungeri, of 

 G-oeppert, from the Cypridina shales of Thuringia. This 

 species appears to be the same with that originally 

 described by Unger as Aporoxylon primigenium. The original 

 description and figures of Unger did not permit an exact 

 comparison, but as now figured by Stenzel ] in his revision 

 of Groeppert's species, it approaches so near to D. Clarkii as 

 to suggest the suspicion that it may be the same, or at least 

 a very closely allied species. The state of preservation, 

 however, is so different that it is scarcely possible to be sure 

 as to this. 



With reference to the generic names, there has been great 

 misconception among pakeobotanists as to the distinction 

 between stems of Cordaioxylon and Badoxylon. This does 

 not at all depend on the occurrence of an Artisia or Stern- 

 bergia pith, which may be present in Sigillaria?, Cordaites 

 or Conifers, as it is indeed in young shoots of modern firs, 

 as well as in angiospermous exogens of different genera. 

 The real distinction is in the character of the inner vessels 

 or fibres of the wedges, the peculiar nature of the medullary 

 rays, and the thinness of the woody cylinder in Cordaites. I 

 have no hesitation on these grounds in referring IK Clarkii 



1 Royal Academy of Berlin, 18S8. 



