456 Scientific Proceedings, Royal Dublin Society. 



tangential direction. Parenchymatous laminae absent in thickness of. 

 70 mm. Sp. gr. = 0-58. 



C.S. — Vessels rounded, isolated, or in small groups of 2 or 3 "divided." 

 M.T.D. = 0-30 mm. 4-7 in 2-mm. field. All filled with tyloses.— Fibres 

 thin-walled, 2-10 between rays. — Circumvasal parenchyma radially 1-3 cells 

 thick, tangentially 4-10 cells thick. — Rays distinct. 



T.S. — Rays fairly uniform in size, irregularly distributed, about 55 in 

 2-mm. field. Total width in 2 mm. = 0-48 mm. Height = OTO-0-40-0'65 mm., 

 2-16 cells. Width = 0-02 -0-06 mm., 1-, 2-, 3-ply. Margin indistinct, rays 

 often invaded by a single fibre. Crystals in cells frequent. — Fibres septate. 



R.S. — Ray margins partially of vertical cells. 



AFRICAN MAHOGANIES. 



16. Khaya anthotheca. 25. " African walnut." 



17. Khaya senegalensis. 26. " African cedar." 



18. Khaya sp. 27. " Cape Lopez mahogany." 



19. Khaya sp. 28. Pterocarpus sp. 



20. Entandrophragma utile. 29. Trichilia emetica. 



21. Entandrophragma excelsum. 30. Chlorophora excelsa. 



22. Entandrophragma candollei. 31. Baillonella djava. 



23. Aucoumea klaineana. 32. " Moabi." 



24. "African walnut." 



The African mahoganies most usually met with in commerce appear to be 

 furnished principally by three genera, viz. : Khaya (Meliaceae), Entandro- 

 phragma (Meliaceae), and Aucoumea (Burseraceae). 



The woods of these three genera which I have examined are easily 

 distinguished from one another by the following microscopic characteristics : — 



Khaya, A. Juss. Also called African, Assinee, Axim, Benin, Bonaniba, 

 Gambia, Gold Coast, Grand Bassam, Lagos, Nigerian, Ombega, Sekondi, 

 Zamingila mahogany. 



C.S. — -Parenchymatous laminae absent, or rare and occasional. Scattered 

 parenchyma rarely noticeable. Circumvasal parenchyma inconspicuous, 

 usually discontinuous, and not more than one cell thick. Vessels often with 

 dark deposit. There are no tyloses. Fibres moderately thick-walled and 

 polygonal. 



T.S. —Rays 1-7 -ply. Margin often several cells deep. Fringe-cells often 



