436

In the specimen depicted Plate IV. Fig. 5, a circumstance is ob-servable, which is, in this place, highly deserving of observation.Lhvvydd and others remark, that sometimes, though rarely, the leafwill be found so well preserved, that even the colour may be dis-cerned : and in this specimen the marks of the leaves are evidentlyof a very dark olive green. But an accurate inspection with a lensdemonstrates that the same circumstance has occurred here, whichis frequently met with in the bituininization of w r ood—the bitumi-nous matter retains the colour of the vegetable substance fromwhich it derived its origin—that which appears to be the leaf beingevidently a thin shining bituminous film.

Yours, &c.

LETTER XLVII.

FOSSIL FLOWERS....THEIR EXISTENCE DOUBTFUL....FOSSIL SEEDSAND SEED VESSELS....FOSSIL FRUITS.

When the extreme delicacy of structure is considered, whichbelongs to the flowers of plants, little expectation can be enter-tained of often finding these in a petrified state. The tender andalmost succulent substance of the petals, stamina, and pistilla,will furnish very little reason for supposing, that they should resista destructive resolution, sufficiently long to allow them to passthrough those chemical changes, by which such duration wouldbe given to their original forms, as would secure their passingunchanged, in their figure, from the vegetable to the mineralkingdom.