XVI 
INTRODUCTION. 
those who write descriptions to use language of greater 
precision. 
In conclusion it may be proper to state, that for any 
opinions expressed in this Introduction, as also for all 
the alterations made in this edition, Dr. Walker-Arnott 
holds himself solely responsible, Sir William Hooker 
having been prevented, by his public duties, from taking 
any part in its revision. 
1st October, 1860. 
