XLIV] DADOXYLON 181 



age. The lack of satisfactory knowledge with regard to the mor- 

 phology of the reproductive organs of such genera as Walchia, 

 Voltzia, and other plants closely resembling living Araucarias in 

 the habit of their foliage-shoots precludes any definite statement 

 as to the precise degree of relationship between these and other 

 types and existing Araucarineae, though it is certain that the 

 Araucarineae were at least foreshadowed before the close of the 

 Palaeozoic era. 



Dadoxylon keuperianum (Goepp.). 



This species 1 , from Franconia and Wurtemberg, is considered 

 by Schimper 2 on the ground of association to be the wood of 

 a Voltzia, and Tuzson 3 adopts the generic name Pagiophyllites 

 implying relationship with Pagiophyllum] he includes in D. 

 keuperianum the species Araucarioxylon wiirtembergicum Kr. and 

 A. thuringicum Born 4 . The tracheids of D. keuperianum have 

 one or more rows of contiguous and more or less flattened pits; 

 the medullary rays are uniseriate and 2 50 cells in depth ; 

 Tuzson figures 2 4 circular simple pits in the field. Though 

 possibly belonging to Voltzia or Pagiophyllum this wood is best 

 retained in Dadoxylon. Other Triassic Dadoxylons are described 

 by Wherry 5 from Pennsylvania: he records Araucarioxylon vir- 

 ginianum, a species described by Knowlton 6 from Potomac beds, 

 and A. vanartsdakni : in both forms the tracheal pits are com- 

 pressed and alternate, the rings of growth indistinct, and the 

 medullary-ray cells are said to have no pits. Reference has 

 already been made to a Triassic species from New Caledonia, 

 D. australe (Crie). 



Dadoxylon septentrionale Gothan. 



This species 7 , founded on material believed by Gothan to be 

 Triassic in age, has the following characters : Annual rings often 

 tinct macroscopically but microscopically showing little con- 

 trast between spring- and summer-wood ; bordered pits in a single 

 row and separate or polygonal and in two alternate rows ; they are 



If ten arranged in stellate clusters as in some species of Cedroxylon. 

 1 Goeppert (81) p. 42. 2 Schimper (72) A. p. 384. 



3 Tuzson (09), p. 30, fig. 5. 4 Schimper (72) A. p. 384. 



5 Wherry (12). Knowlton (89 2 ), PL vn. figs. 25. 



7 Gothan (10) p. 8, PL r. figs. 48, PL n. fig. 1. 





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