270 DESCRIPTIVE CATALOGUE 



TOPOGRAPHY OF THE STKM. Pith and primary wood are not 

 preserved. Secondary wood is very " light " and porous in struc- 

 ture, with a large proportion of wood-parenchyma both adjacent 

 to the vessels and scattered, relatively thin-walled wood-fibres, 

 and very numerous large vessels close to each other. The 

 isolated vessels are evenly distributed throughout the whole 

 mass of the wood. 



Grotuth-rinc/s are not present, but the greatest radial diameter 

 of the specimen is only 2-5 cm., and though that is much wider 

 than the average growth-zones in timber, such a loosely-textured, 

 probably quick-growing, wood as this may have had very excep- 

 tionally wide growth-zones, and the specimen may come within 

 either limit of a single zone. On the other hand, growth-zones 

 are often absent in tropical or subtropical woods. 



Medullary rays are principally multiseriate, about 4-8 cells 

 wide ; smaller interspersed rays, two cells wide, are numerous. 

 The rays are high, many being 40-60 cell-rows in vertical 

 series. The ray-cells are poorly preserved, but seem all alike, 

 and without special differentiation. 



DETAILS OF THE ELEMENTS. The wood-vessels are roughly 

 circular, nearly all isolated and very large, measuring on an 

 average from 280- 370 p. in diameter (text-fig. 80). In longi- 

 tudinal view the outlines of the adjacent elements mark areas 

 on the walls of the vessels, which are irregularly covered with 

 small, bordered, irregularly oval pits (text-fig. 81). Wood- 

 fibres are slightly hexagonal or circular, and are in groups 

 isolated or in alternating rows among the parenchyma (text- 

 rig. 80, a. & >.). Their walls are thickened, but not excessively 

 so, as can be seen in the figure. They have pointed ends, and, 

 adjacent to the vessels, appear to have bordered pits (text- 

 fig. 81). Wood-parenchyma is much developed, but the details 

 of the cell-walls are not well enough preserved for description. 



The individual cells composing the medullary rays appear to 

 be all alike, to have a squarish or rectangular shape in radial 

 section, with oval pits in their radial walls, but they are too 

 poorly preserved to be described in detail. 



AFFINITIES. The striking contrast in texture between this 

 Avood and that of Aptiana (see p. 284) is very remarkable. If, 

 as in many respects one might have pre-supposed, the small size 

 of the vessels and their regular sequence in the radial series of 



