1914] HOLDEX— CRETACEOUS LIGNITES 173 



are low (figs. 23, 24) , with thin unpitted walls. All the parenchyma, 

 both radial and longitudinal, whether in pith, wood, or bark, is 

 filled with a dense black substance. The structure of the phloem 

 is shown in fig. 22. It consists of rays, sieve tubes, parenchyma 

 cells, and also bast fibers. These last are usually more or less 

 crushed, but it is not difficult to see that they occur in tangential 

 rows, alternating with rows of soft bast, just as in the case of the 

 Brachyoxylon twig described above. It is noteworthy that in the 

 former specimen the soft bast collapsed and the hard retained its 

 natural size, while here just the reverse is true. On account of the 

 absence of bars of Sanio, such a wood as this, though strictly speak- 

 ing a Cupressinoxylon, cannot be affiliated with other members of 

 that genus, e.g.. Juniper us, Cupressus, Sequoia, etc. On the con- 



affiliations must 



The type genus 



Paracedroxylon was founded by Sinnott 5 to include wood which is 

 Cedroxylon in everything but bars of Sanio; and for similar Cu- 

 pressinoxyla the genus Paracupressinoxylon was established. 6 Two 

 species were described. The first, Paracupressinoxylon cedroides, 

 resembles the Cliff wood specimen in question in absence of medul- 

 lary stone cells, but differs in having thick-walled, heavily pitted 

 rays like a Cedroxylon. The second, P. cupressoides, lacks pith and 

 bark, but has exactly the wood structure of this Cretaceous 

 twig from Cliffwood. It seems safe, accordingly, to include 



both specimens as P. cupressoides, in spite of the difference in 

 horizon . 



The stem just described, although the most abundant of the 



Cup 



one without stone cells in the pith. 



Figs. 25-28 represent a more common type. In the medulla may 

 be seen groups of sclerites, and in the wood the scattered paren- 

 chyma cells. Fig. 27 shows the low rays and well spaced pits 

 characteristic of the mature wood of this twig. Fig. 28 shows the 

 structure near the pith. The pits here, instead of being distant, 

 are fairly close, and are in several places separated by bars of Sanio. 



5 Sinnott, Edmund, A. \V.. Paracedroxylon. a new type of araucarian wood. 

 Rhodora 11:165-173. ph. 80, 81. 1909. 



* Holden, Rlth. Jurassic coniferous woods from Yorkshire. Ann. Botany 

 2 7 : 5*3-545. ph. 39, 40. 1913. 



