DESCRIPTION OF PLATES. 



The figures on Plates 1 to 8 and figures 1 to 4 on Plate 13 are the original figures 

 accompanying Doctor Troost's monograph. They were drawn by Major A. Heiman. 

 All other figures are from original drawings or from photographs retouched by the 

 author. 



All figures are of natural size unless otherwise stated. 



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