17.: 



During a long official career, with special experience arising out of much travel, 

 and the care of a rich botanic garden and herbarium, I have had frequent experience 

 of the way in which the average citizen firmly believes that the botanist can name a 

 plant from a leaf. One has to tell him that unless the leaf is characteristic and well 

 known, naming becomes a guess. With fresh leaves (and to a less extent with dry ones) 

 we have an upper and lower surface, and can examine colour, texture, thickness, smell, 

 taste, &c, but what shall we say of the disabilities of those botanists who determine 

 plants from impressions, frequently of one surface, and frequently poor impressions 

 and broken. In a fossil species we can measure the approximate angle the secondary 

 veins make with the midrib, and we can note the shape of the leaf, a very variable thing- 

 When I arrive at consideration of the Mature Leaf, I shall offer details of the angles of 

 the leaves of Fossil species and make comparisons and deductions. 



I follow the great Bentham in his remarks already quoted. I have often been 

 requested to express an opinion as to supposed fossil Eucalyptus remains, but, as a very 

 general rule, an affirmative expression of opinion would, as regards the specimens 

 submitted to me, require such an exercise of the imagination as seemed to me not justified. 

 I attach importance to the opinions of men such as Bentham (although he protests 

 his ignorance of palaeontology), Johnston and Deane, who knew and know the living 

 genus. 



The variation in leaves in Australian and other plants has been emphasised in 

 my mind through the researches of one of my late assistants (Mr. A. A. Hamilton), 

 who has specialised in making collections of leaves from individual species of various 

 genera and families, showing the startling variation which can only be ascertained 

 by actually making and viewing such collections. I am quite certain that one cannot 

 realise the amount of foliar variation without examination of such special collections 

 as those to which I have referred. It is quite impossible to bear them in mind in a 

 general way unless they are specially brought together. 



A.— AUSTRALASIAN. 



I give serial numbers, together with descriptions and figures, of the following 

 fossil plants, all of them found in Australia and Tasmania, because I look upon them 

 as Eucalypts (with a possible reservation in regard to some of those referred to the 

 Cretaceous). 



C 



