s; but
there are, in addition, phaenomena exhibited by species themselves, and
yet not so much a part of their very essence as to have required earlier
mention, which are in the highest degree perplexing, if we adopt the
popularly accepted hypothesis. Such are the facts of distribution in
space and in time; the singular phaenomena brought to light by the study
of development; the structural relations of species upon which our
systems of classification are founded; the great doctrines of
philosophical anatomy, such as that of homology, or of the community of
structural plan exhibited by large groups of species differing very
widely in their habits and functions.

The species of animals which inhabit the sea on opposite sides of the
isthmus of Panama are wholly distinct;[63] the animals and plants which
inhabit islands are commonly distinct from those of the neighbouring
mainlands, and yet have a similarity of aspect. The mammals of the
latest tertiary epoch in the Old and New Worlds belong to the same
genera, or family groups, as those which now inhabit the same great
geographical area. The crocodilian reptiles which existed in the
earliest secondary epoch were similar in general structure to those now
living, but exhibit slight differences in their vertebrae, nasal
passages, and one or two other points. The guinea-pig has teeth which
are shed before it is born, and hence can never subserve the masticatory
purpose for which they seem contrived, and, in like manner, the female
dugong has tusks which never cut the gum. All the members of the same
great group run through similar conditions in their development, and all
their parts, in the adult state, are arranged according to the same
plan. Man is more like a gorilla than a gorilla is like a lemur. Such
are a few, taken at random, among the multitudes of similar facts which
modern research has established; but when the student seeks for an
explanation of them from the supporters of the received hypothesis of
the origin of species, the reply he receives is, in substance, of
Oriental simplicity and brevity--"Mashallah! it so pleases God!" There
are different species on opposite sides of the isthmus of Panama,
because they were created different on the two sides. The pliocene
mammals are like the existing ones, because such was the plan of
creation; and we find rudimental organs and similarity of plan, because
it has pleased the Creator to set before himself a "divine exempla