ew
variety raised by man will be a more important and interesting subject
for study than one more species added to the infinitude of already
recorded species. Our classifications will come to be, as far as they
can be so made, genealogies; and will then truly give what may be called
the plan of creation. The rules for classifying will no doubt become
simpler when we have a definite object in view. We possess no pedigree
or armorial bearings; and we have to discover and trace the many
diverging lines of descent in our natural genealogies, by characters of
any kind which have long been inherited. Rudimentary[1] organs will
speak infallibly with respect to the nature of long-lost structures.
Species and groups of species which are called aberrant, and which may
fancifully be called living fossils, will aid us in forming a picture of
the ancient forms of life. Embryology will often reveal to us the
structure, in some degree obscured, of the prototypes of each great
class.

When we can feel assured that all the individuals of the same species,
and all the closely allied species of most genera, have, within a not
very remote period descended from one parent, and have migrated from
some one birth-place; and when we better know the many means of
migration, then, by the light which geology now throws, and will
continue to throw, on former changes of climate and of the level of the
land, we shall surely be enabled to trace in an admirable manner the
former migrations of the inhabitants of the whole world. Even at
present, by comparing the differences between the inhabitants of the sea
on the opposite sides of a continent, and the nature of the various
inhabitants on that continent in relation to their apparent means of
immigration, some light can be thrown on ancient geography.

The noble science of geology loses glory from the extreme imperfection
of the record. The crust of the earth, with its imbedded remains, must
not be looked at as a well-filled museum, but as a poor collection made
at hazard and at rare intervals. The accumulation of each great
fossiliferous formation will be recognized as having depended on an
unusual occurrence of favourable circumstances, and the blank intervals
between the successive stages as having been of vast duration. But we
shall be able to gauge with some security the duration of these
intervals by a comparison of the preceding and succeeding organic forms.
We must be cautious in attempting to