XXXIIlJ DADOXYLON 255 



Dadoxylon jyrotofityoides FeKx. 



An interesting feature in this Westphalian type from Germany 

 is the occurrence of transversely elongated pits on the tracheids^ 

 associated with those of normal form closely simulating the pits 

 in the xylem elements of Protopitys. 



Dadoxylon nummulwrium White. 



In this Brazilian wood^ from Permo-Carboniferous beds the 

 medullary rays are very numerous, mostly imiseriate and 1 — 30 

 cells in depth. The pits on the tracheids are in 1 — 2 rows and are 

 often contiguous. In another type, D. meridionale, described by 

 the same author^, the pits are strictly uniseriate and generally 

 contiguous. As White says, the absence of the pith and cortex 

 and of any evidence as to the structure of the primary xylem 

 renders impossible any definite expression of opinion as to the 

 affinity of these and many other species. 



Dadoxylon Nicoli Seward. 



Dr Arber* in naming this species, from the Newcastle (Permo- 

 Carboniferous) Series of New South Wales, Dadoxylon australe, 

 does not mention Crie's earlier account of some wood from New 

 Caledonia under the name Araucarioxylon australe^. The latter 

 generic name according to the usage adopted in this volume 

 should be superseded by Dadoxylon, and this necessitates a fresh 

 specific name for Arber's specimens. The name NicoU is suggested 

 in place of australe, as the sections on which Arber founded his 

 species form part of the Nicol collection in the British Museum. 



The xylem shows distinct rings of growth, a feature also seen 

 in Indian stems of approximately the same geological age and 

 recorded by Shirley* in wood from Queensland which needs more 

 careful examination. The bordered pits, usually miiltiseriate 

 and contiguous, are not infrequently in 1 — 2 rows and separate. 

 The uniseriate medullary rays are very numerous as in White's 

 Brazilian species D. nummularium, and as a rule 6 — ^12 cells deep. 

 Some well-preserved specimens from Permo-Carboniferous strata 



' Felix (86) A. PI. v. fig. 4. ^ white (08) B. p. 579, PI. xm. 



3 Ibid. p. 583, PI. XIV. * Arber (05) B. p. 191, figs. 40-^3. 



s Crie (89). « Shirley (98) p. 14; Arber (05) B. p. 201. 



