Dixon — Mahogany, Recognition of some Different Kinds. 443 



In the following descriptions records are given of some of the general 

 characters and microscopic structures of a number of samples of mahogany. 

 The characteristics which have been found of use for identification have been 

 selected. The figure in Clarendon type prefixed to each is the reference 

 number in the key which follows. The number of each specimen described 

 is its number in the collection of woods in the School of Botany, Trinity 

 College, Dublin. The source of the specimen is indicated in each case. 



In the descriptions the following abbreviations are used : — 



Sp. gr. = specific gravity. C. S. = cross section. T. S. = tangential section 

 E. S. = radial section. M. T. D. = maximum tangential diameter (applied to 

 vessels). The greatest number of cells appearing in the cross-section of the rays 

 seen in a tangential section of the wood is written thus : — 1-, 2-, 3-, 4-, 5-, 6-ply. 

 This indicates that rays 1, 2, 3, 4, 5, and 6 cells thick are found, but that those 

 3, 4, and 5 cells thick are most abundant. 



Here I would like to acknowledge my indebtedness for many specimens 

 to the kindness of Mr. E. Olive Brooks of Dublin ; Mr. J. A. Murphy, 

 Messrs. John Holt & Co., McNeil, Scott & Co., and G. B. Walker & Son, of 

 Liverpool; also, the Director of the Imperial Institute, London, the Director 

 of the Boyal Gardens, Kew, the Curator of the Botanic Gardens, Georgetown' 

 Demerara, and the Conservator of Forests, Nigeria, have very kindly assisted 

 me by sending me authenticated samples for this work. Phave also to thank 

 Messrs. Hicks and Strahan of Dublin for several specimens. 



In order to facilitate the use of the descriptions in distinguishing the 

 various kinds of mahoganies here examined, a key is provided which utilizes 

 some of those microscopic features which I have found most characteristic of 

 the various woods. 



Key. 



In the following key of the woods described in this paper the figure before 

 the name of the wood refers to the number placed before its name in the 

 descriptive list of Western, African, Asiatic, and Australasian mahoganies, 

 which follows. 



Mahoganies — Key. 



Vessels in wavy lines (echelon) in C.S., 1 



Vessels scattered in C.S., 3 



I M.T.D. of vessels less than 042 mm. 10. Mimiisops globosa. 



I M.T.D. of vessels more than 042 mm., 2 



' More than 100 rays in 2 mm. field T.S. 13. "Guatemala mahogany." 

 2. \ Calophyttwm sp. ? 



( About 50 rays in 2 mm field, 31. Baillondla dj'ava. 



