460 Scientific Proceedings, Royal Dublin Society. 



C.S. — Vessels circular or tangentially compressed, isolated or in small 

 groups usually of 2 or 3 radially disposed. M.T.D = 0'20-O30 mm. 4-17 groups 

 in 2-mm. field. Often with dark contents. — Fibres thin to moderately thick- 

 walled, polygonal. — Circumvasal parenchyma narrow, usually 1 cell thick and 

 discontinuous. Laminar parenchyma rare or absent, sometimes with deposit 

 of dark gum-like substance in intercellular spaces, and forming a dark 

 tangential band across section (PL XXX., fig. 49). — Eays distinct, sometimes 

 noticeable owing to dark deposit in cells. The fringes of the rays are often 

 conspicuous as single radial series of larger cells. 



T.S. — Fibres rarely non-septate. — Eays irregular in size and arrangement, 

 sides bowed, 30-50 in 2-mm. field. Average height of 6-ply rays = - 45-070 mm. 

 Maximum height = 1"1 mm. Width of 6-ply rays = O'05-O'IO mm. Eaysl-, 

 2-, 3-, 4-, 5-, 6-, 7-ply, rarely 10-ply. Margin distinct, often with crystals in 

 cells. 



E.S. — Margin of rays of square or iso diametrical polygonal cells and fringe 

 of palisade cells. 



Note. — With the small number of authentically named specimens it has 



been found impossible to distinguish with certainty between the species 



Khaya, senegalensis, K. grandis, and K. pnnchii. The rays of K. punchii are 



often 1 mm. high, their marginal cells frequently contain crystals, and often 



the rays are covered on the sides as well as on margin by a sheath of large 



cells. In K. grandis and in K. senegalensis this lateral sheath is absent, and 



the rays seldom attain heights of - 6 mm. and - 8 mm. respectively. 



Crystals in the marginal cells are frequent in K. grandis and rare in 



K. senegalensis. The extract from these two is much paler than that from 



K. punchii. " 



18. Khaya, sp. ? (Type III.). 



No. 76, from commercial source, marked "African mahogany, Axim." 



PI. XXXI, figs. 58, 59, 60. 



Lustrous, dark rose brown, roey, alternate dense (dark), and open zones 

 grade into one another. Vessels sparser in dense zones. Vessels with dark 

 contents. No parenchymatous laminae in 9 cm. Eays pink. Sp. gr, = - 53. 

 . . C.S. —Vessels tangentially compressed, scattered, M.T.D. = 0-25, 10-14 

 groups in 2-mm. field, with dark contents. Circumvasal parenchyma with 

 open lumina. — Fibres thin-walled, often with contents adjacent to rays. — 

 Eays usually empty. 



T.S. — Fibres non-septate. — Eays irregular, bowed, finely pointed, about 40 

 in 2-mm. field, total width of rays in 2 mm. = - 44 mm. Height = 110 up to 

 200 mm. Width = 0-077. 1-, 2-, 3-, 4-, 5-, 6-, 7-ply. Margin often several 

 cells deep, crystals occasional. Middle cells small, angular, mostly empty. 



