It has been acknowledged by botanists that the methods generally pursued in determining fossil dicotyledonous plants have been scarcely such as were likely to lead to trustworthy results. Their study has, or should have, two practical aims. The one, that geologists may be able to determine the ages of strata, when they only contain fossil plants, with as much certainty as if they contained the remains of animals. The other, that botanists may be able to trace the evolution of the existing genera of plants from the pala?ontological record under conditions no less favourable than those at the disposal of the zoologist.