As a definite instance a short review may be given of the evidence of palaeobotanical records as regards their bearing on plant-evolution.
The change to this newer type of vegetation was no doubt less sudden than it appears as read from palaeobotanical records, but the transition period between the Palaeozoic type of vegetation and that which flourished in the Lower Mesozoic era, and continued to the close of the Wealden age, was probably characterized by rapid or almost sudden changes.
Palaeobotanical literature contains several records of species of -Lycopodites and Selaginellites; Lycopo- nearly all of them are sterile fragments, bearing a more diates.
Before considering the results of palaeobotanical research, some account must be given of the way in which the evidence is presented, or, in other words, of the modes of preservation of vegetable remains.
The application of the important criteria which Bower has thus pointed out to the construction of a strictly phylogenetic classification of the Filicaceae cannot be made until the anatomy, the sexual generation and the palaeobotanical evidence have been further examined from this point of view.