than the fossil remains of vegetables. In the former, the entire figure 
of the investiture of the animal is sometimes preserved ; and where 
this is not the case, sufficient is frequently found, to point out the 
genus, and in many cases^ ev^n the species of the animal : but pieces of 
wood, leaves, with the kernels and coriaceous coverings of fruits, can 
seldom do more than lead to uncertain conjecture, respecting the natural 
order or class under which the plant should be placed. 
It is my intention, whilst proceeding to inform you of the result of 
my investigations, to continue to place them before you in an episto- 
lary form. This is indeed rendered necessary, in some degree, by 
that form having been adopted in the preceding volume. But, inde- 
pendent of that circumstance, it is the form which, for several other 
reasons, I am disposed to prefer. By adopting this mode, I shall feel 
myself more at liberty to introduce such matter as, although highly 
useful in illustration, might hardly perhaps be admissible in a work 
composed according to the more rigid forms, in which disquisitions of 
this kind are generally presented to the world. The epistolary stile 
too appears to be well suited to the discussion of subjects of natural 
history. It allows that familiar mode of expression, which seems to be 
best calculated for those illustrations which are required by the various 
topics, which this study embraces. It also admits of the introduction 
of those reflections, which although, perhaps, not unacceptable, and 
which naturally arise from the immediate subject of inquiry, might 
appear to be too digressive, in a work written in a truly systematic 
form. But another circumstance, it must be admitted, has had some 
considerable weight in determining this choice. These observations 
have been put to paper, at short and uncertain periods, when the 
fatigue arising from professional labours has left the mind in such a 
state, as to render it necessary to record the results of its investiga- 
tions, in that familiar kind of stile as might best suit the writer in 
such moments ; and as might not demand the extreme severity of cri- 
ticism. 
