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XVII. — On the Primary Structure of certain Paleozoic Stems with the Dadoxylon 

 Type of Wood. By D. H. Scott, M.A., Ph.D., F.E.S., Hon. Keeper of the 

 Jodrell Laboratory, Koyal Botanic Gardens, Kew. Communicated by Professor 

 I. Bayley Balfour, F.R.S. (With Six Plates.) 



(Read January 6, 1902. Issued separately April 7, 1902.) 



In a Note published in the Annals of Botany for December 1899,* I gave some 

 account of the structure of two stems from the Lower Carboniferous of Scotland, 

 provisionally named Araucarioxylon fasciculare, sp. nov., and A. antiquum, Kr. 

 (Witham, sp.). 



In the present paper these stems are described fully, with the help of illustrations, 

 and others, presenting similar points of interest, are added. The species dealt with are 

 the following : — 



Calamopitys fascicidaris (Araucarioxylon fasciculare of the Note). 

 Calamopitys beinertiana (Araucarioxylon beinertianum, Kr.), (Gopp., sp.). 



Pitys antiqua, Witham (Araucarioxylon antiquum, Kr. of the Note). 

 Pitys Withami (Pinites Withami, Lindl. & Hutt.). 

 Pitys primazva, Witham. 



Dadoxylon Spenceri, sp. nov. 



The reasons for the nomenclature adopted will be given in each case when the 

 structure has been described. It was stated in the Preliminary Note that the two 

 stems there described would certainly require generic separation on the basis of their 

 primary characters (I.e., p. 619). This has now been done, but I have succeeded in 

 avoiding the creation of any new genus, for in the one case the characters appeared to 

 indicate the genus Calamopitys of Unger as the appropriate one, while in the other the 

 use of Witham's old generic name, in an emended sense, seemed to meet the case. 



Where the old genus Dadoxylon or Araucarioxylon has to be kept up, I agree 

 with Knowlton t and Zeiller \ that the former name is to be preferred in the case of 

 Palaeozoic woods, restricting Araucarioxylon to Secondary or Tertiary specimens, which 

 may more probably be referred to true Araucariese. The use of the name Araucari- 

 oxylon for Palaeozoic specimens, probably belonging to the Cordaitese, or to 

 some other family equally remote from true Araucariese, is likely to mislead, and 

 though I employed this name in the Preliminary Note, I now think it better to 

 avoid it. 



* " On the Primary Wood of certain Araucarioxylons" Ann. Bot., vol. xiii. p. 615. 



t " A Revision of the Genus Araucarioxylon of Kraus," Proc. U.S. Nat. Mus., vol. xii. p. 601, 1890. 



X Elements de Pattobotanique, p. 279, 1900. 



TRANS. ROY. S0C. EDIN., VOL. XL. PART II. (NO. 17). 3 d 



