structures in an embryonic or arrested condition, such as a cleft palate,
bifid uterus, etc., are frequently accompanied by polydactylism. This has
been strongly insisted on by Meckel and Isidore Geoffroy St.-Hilaire. But
at present it is the safest course to give up altogether the idea that
there is any relation between the development of supernumerary digits and
reversion to some lowly organised progenitor of man.) There are other
cases which come more strictly under our present head of reversion.
Certain structures, regularly occurring in the lower members of the group
to which man belongs, occasionally make their appearance in him, though not
found in the normal human embryo; or, if normally present in the human
embryo, they become abnormally developed, although in a manner which is
normal in the lower members of the group. These remarks will be rendered
clearer by the following illustrations.

In various mammals the uterus graduates from a double organ with two
distinct orifices and two passages, as in the marsupials, into a single
organ, which is in no way double except from having a slight internal fold,
as in the higher apes and man. The rodents exhibit a perfect series of
gradations between these two extreme states. In all mammals the uterus is
developed from two simple primitive tubes, the inferior portions of which
form the cornua; and it is in the words of Dr. Farre, "by the coalescence
of the two cornua at their lower extremities that the body of the uterus is
formed in man; while in those animals in which no middle portion or body
exists, the cornua remain ununited. As the development of the uterus
proceeds, the two cornua become gradually shorter, until at length they are
lost, or, as it were, absorbed into the body of the uterus." The angles of
the uterus are still produced into cornua, even in animals as high up in
the scale as the lower apes and lemurs.

Now in women, anomalous cases are not very infrequent, in which the mature