Dixon — Mahogany, Recognition of some Different Kinds. 445 



- ( More than 60 rays in 2 mm. field T.S. 19. Khaya sp. 



( Less than 60 rays in 2 mm. field T.S., 16 



\ Average height of rays about l\Lti mm. 18. Khaya sp. (Axim). 



\ Average height of rays about 0"70 mm. or less, 17 



( 30-50 rays in 2 mm field T.S. 17. Khaya senegalensis. 



\ Less than 30 rays in 2 mm. field T.S. 16. Khaya anthotheca. 



( Parenchymatous laminae frequent (1 or 2 in 10 mm.), 19 



) Parenchymatous laminae rare or absent 31 



j Parenchymatous laminae distinct, 4 or more cells thick, 20 



I Parenchymatous laminae indistinct and thin, 29 



[ Parenchymatous laminae about 5'0 mm. or more apart, 21 



20. < Parenchymatous laminae close in outer regions of growth-zones, 



( 1 mm. or less apart, 27 



( Circum vasal parenchyma spreading tangen fcially. 



21. | 24. " African walnut." 



( Circum vasal parenchyma not spreading tangentially, : 22 



( Margin of rays indistinct. 6. Protium altissimum. 



\ Margin of rays distinct 23 



I Vessels distinctly grouped in zones. (" Eing Porous.") Pay cells 



23. < bulging into fibres, Cedrela, 24 



' Vessels indistinctly zoned. Pay cells not bulging, Swietenia, 26 



j Pays 1-, 2-, and 3-ply. 35. Cedrela serrata. 



\ Pays 1-, 2-, 3-, 4-, 5-ply, 25 



Circum vasal parenchyma 3-6 cells thick. Some scattered paren- 

 chyma. 3. G. odorata 



Circumvasal parenchyma inconspicuous. Little or no scattered 



parenchyma. 33. C. toona. 



Average height of rays less than - 45 mm. 



1. 8. mahagoni. 

 Average height of rays more than 0-45 mm. 



2. S. macrophylla. 



Pays blunt in T.S., mostly 4-ply, 22. Entandrophragma 



candollei. 

 Pays acute in T.S., seldom 4-ply, 28 



Parenchymatous laminae undulating in C S. 



20. Entandrophragma utile. 

 Parenchymatous laminae not undulating in C.S. 

 \ 21. E. excelsum. 



25. ] 



26. 



28. 



