464 Scientific Proceedings, Royal Dublin Society. 



Nos. 221 and 300. Its rays are more uniform in size, being composed of 

 about 15 tiers of cells, while the rays of the other two are on the average 

 about 25 cells high. The width of the rays of the former is about 0-08 mm., 

 and of the latter about O'Od mm. 



23. Aueoumea Maineana. 

 No. 42, from commercial source, labelled " Gaboon mahogany." 

 No. 66, from commercial source, labelled " Gaboon mahogany." 

 No. 67, from commercial source, labelled " Gaboon mahogany." 



PI. XXXV., figs. 79, 80, 81. 

 No. 68, from commercial source, labelled " Gaboon mahogany." 

 No. 283, from commercial source, labelled " Okoumie, known in European 

 markets as Gaboon mahogany." 



No. 284, from commercial source, labelled " Zamingila or Ombega " ; but 

 certainly quite unlike in structure the wood usually called by those names, 

 which is a species of Khaya (cf. No. 285, PL XXXI., figs. 55, 56, 57), and 

 closely similar to the foregoing samples, from which it differs only in the 

 greater number of vessels seen in cross-sections (viz., as many as 50 per 

 2 mm. field), and having a density above the average (viz., sp. gr. = - 50). 

 The naming shows that dense and fairly dark samples of the wood of 

 Aucoximca Jdaineana may easily be mistaken for that of Khaya sp., unless 

 microscopic structure is observed. 



No. 307, from commercial source, labelled " Gaboon mahogany ; 

 Cameroons." 



No. 308, from commercial source, labelled " Gaboon mahogany ; 

 Cameroons." 



Colour varies from pale flesh-colour to red brown or pink brown. The 

 longitudinal surfaces are lustrous and roey. The cross-cut is horny or semi- 

 translucent, often exhibiting dark and light bands alternating. The transition 

 from dark to light may be abrupt on either side, or, more usually, the inside 

 of each growth-zone is light, and grows denser gradually towards the outside. 

 The beginning of the next zone is marked by an abrupt transition from dense 

 to light wood. The vessels are usually scattered uniformly, and do not avoid 

 the dense zones Sometimes an indistinct zoning of the vessels is also found 

 (e.g., No. 284). Again, all zoning both of vessels and fibres may be absent. 

 There are usually no parenchymatous laminae to be seen over wide distances. 

 The rays are fine and paler pink than the adjoining tissues, sinuous and 

 threading their way between the vessels. Sp. gr. =. 0-34-0-50. 



C-S. — Vessels isolated or in small groups, usually somewhat tangentially 

 compressed, M.T.D. = 0T8-0-31 mm,, 5-20 groups in 2-mm. field. (Earely, 



