On a former page (_anteà_, p. 13), attention was drawn to the interrupted
distribution of the Lemurs, and to their present restricted range to the
tropical and sub-tropical regions of Africa, of Madagascar, and of part of
the mainland and of the islands of the Asiatic continent. In times
geologically not very remote, they were inhabitants of both worlds.
The earliest appearance of the Primates in time is at the beginning of the
Tertiary period. Lemuroids, some of them of a more or less primitive type,
then lived in Europe in the Lower Eocene period. In the higher beds of the
same epoch (to which the fresh-water deposits of the London clay of
England, the Plastic clay of France, and the prolific Wasatch beds of
Wyoming, Utah, and Colorado of America belong) undoubted Lemurs are
represented by many genera, which in the Middle Eocene attained to a great
development.
In the Upper Eocene of Europe many distinctively {111}Lemuroid genera
(_Adapis_, _Microchærus_, &c.) "formed," as Zittel remarks, "a very
characteristic element of the fauna; they are connected with old Tertiary
fore-runners, and combine features of the existing Lemurs and true Apes."
The presence of these heat-loving animals in such northern latitudes
undoubtedly indicates the existence there of a climate more genial at that
epoch than now. In the corresponding period in North America remains have
been less plentifully found; but for the most part the genera are
representatives of those of the European beds.
In strata of Oligocene and older Miocene age no Lemuroid remains have come
to light in Europe, and they are represented by only one or two doubtful
forms in America. After that date they apparently vanished from the New
World and from the northern portions of the Old.
Many of these extinct Lemuroids so combine the characters of the
_Insectivora_ and the _Ungulata_ (or hoofed animals), with those of their
own Sub-order, that it is often extremely difficult, even impossible,
sometimes, to determine to which Order they really belong, owing to a
blending of characters due to their common origin. The Upper Eocene forms
present many affinities with the South American Capuchin Monkeys
(_Cebidæ_). Dr. Forsyth Major is of opinion, however, that they are more
highly, and not (as is generally believed) less specialised than those now
living, which appear to have been the subject of retrogressive development.
The species to be noticed below are some of the more important of those
which have been ascertained to belong to the present Sub-order.
No remains assignable with certainty to the families _Chiromyidæ_ or
_Tarsiidæ_, have as yet been discovered. The first form {112}to be
mentioned belongs to a family which has now no living representatives.