Dixon — Mahogany, Recognition of some Different Kinds. 461 



19. Khaya, sp. ? (Type IV.). 



No. 41. Richly figured specimen, dark brown, from commercial source, 

 labelled " African mahogany." 



Longitudinal surface lustrous and roey. Cross-sections zoned dark and 

 light, with irregularly and often widely spaced parenchymatous laminae, 

 sometimes occupied with dark deposit. PI. XXXII., figs. 61, 62, 6-.1. 



Sp.gr. = 0-76. 



C.S.— Vessels scattered, indistinctly zoned. M.T.D. = 0-14 mm. About 

 10 groups in 2-nim. field, often with dark contents. — Fibres thick-walled. 

 Circumvasal parenchyma often thick, spreading irregularly, and usually 

 filled with dark deposit. Parenchymatous laminae thick, widely and 

 irregularly spaced. Scattered parenchyma in places abundant, and tending 

 to adhere to rays and to form narrow, irregular laminae. All parenchyma 

 filled with dark deposit. — Rays with dark contents. 



T.S. — Fibres septate. — Rays irregular in size and arrangement, 80-100 in 

 2-mrn. field. Total width in 2 mm. = 0'56 mm. Average height of 6-ply 

 rays = 0-50 mm. "Width = 0'06 mm. Rays 1-, 2-, 3-, 4-, 5-, 6-, 7-ply, many 

 8-9 or 10-ply in places. Margin of rays several tiers deep. All cells of 

 rays may be blocked with dark contents. 



R.S. — Marginal cells of rays square or isodiametrical and polygonal. 

 Palisade fringe. Inner cells with rectangular walls. 



Entandrophragma. 



The microscopic structure of the woods presumably furnished by species 

 of Entandrophragma, which have come under my observation, seem to divide 

 these woods into three types : — 



Type I. — Entandroiphragvm utile, with undulating parenchymatous laminae 

 1-4 cells thick, 4-10 groups of vessels in 2 mm. field. The height of the rays 

 averages - 50 mm., and there are about 35 rays in 2 mm. field in tangential 

 sections. Rays mostly 2- and 3-ply. PI. XXXIIL, figs. 70, 71, 72. , 



Type II. — Entandrophragma excelsum has flat parenchymatous laminae 

 2-10 cells thick, about 20-30 groups of vessels in 2 mm. field of cross-sections. 

 The height of the rays averages between 0'30 mm. and - 40 mm., and there 

 are about 50 rays in a 2-mm. field in tangential sections. Rays mostly 2- 

 and 3-ply. PI. XXXIIL, figs. 67, 68, 69. 



Type III. — Entandrophragma candolhi — (Scented Sapele Mahogany) has 

 flat and undulating parenchymatous laminae 2-10 cells thick, about 20-30 

 vessels in 2-mm. field of cross-sections. The height of the rays averages 

 between 0-45 mm. to 0*55 mm., and there are about 30-35 rays in 2 mm. field 

 of tangential sections. Rays mostly 4-ply. PI. XXXIV., figs. 73, 74, 75, 



