GUIDE TO TIMBERS OF NIGERIA 97 



FIG. 2. Brachystegia. The P. (a) sheathing the vessels is in 

 somewhat lozenge-shaped patches, and sometimes unites two 

 pore-groups. A fine sub-continuous line of P. (c), together 

 with a denser pore-less zone of wood, appears to form the 

 limit of the ring. 



FIG. 3. Erythrophleum. A less pronounced type than fig. 2. 

 The lozenge-shaped sheaths and the ring-boundaries are but 

 little developed, 



FIG. 4. Afzelia ? A modification of the type in fig. 2, the 

 lozenge-shaped patches around the vessels being well shown, 

 as is also the very fine boundary-line (just visible in the 

 figure). 



FIG. 5. Piptadenia. The P. (a) is well developed, but only as 

 aureoles or annular sheaths around the vessels." 



FIG. 6. Casearia (pith side to right below). The P. (a) very 

 narrowly sheathes the vessels, but sufficiently to make them 

 apparent. The vessels tend to arrange themselves into 

 straggling, radial series. 



PLATE IV 



TRANSVERSE SECTIONS, PITH SIDE DOWNWARDS, x. 3, PHOTO- 

 GRAPHED FROM THE SOLID WOOD BY A. J. WILSON 



FIG. 1. Sarcocephalus. The P. (a) is just visible sheathing the 

 vessels. The vessels tend to crowd in the badly- grown rings 

 and to thin out in the wider ones. 



FIG. 2. Khaya. This is the usual type of the Mahoganies 

 (Meliaceae), but very little is to be made out from a photo- 

 graph. The boundary lines of P. (c), which can just be seen, 

 are absent in some of the African Mahoganies. The vessels 

 are rare and widely isolated in some places. 



FIG. 3. Lovoa. A very common type amongst the Meliaceae. 

 The sheaths or aureoles of P. (a) are visible around the vessels, 

 but the latter are rarely if ever joined together by them. 

 There is a tendency to oblique lines amongst the vessels. 

 The two dark parallel lines (top) are rows of " gum-galls." 



FIG. 4. Scotellia. The tissue contains very little Parenchyma ; 

 the vessels are small and close ; the rays (running vertically) 

 are rather large. 



FIG. 5. Terminalia superba. The festoons of P. (a) can hardly 

 be made out. They connect the very rare, widely isolated 

 vessels. The boundary-zone of dense wood is very char- 

 acteristic of this wood. 



FIG. 6. Terminalia sp. This appear? to be of quite a different 

 type to the last as the P. (a) is very little developed indeed. 



