The Aye-aye, (Chiromys), the sole representative of this family, is confined to the island of Madagascar. It was for a long time very imperfectly known, and was supposed to belong to the Rodentia; but it has now been ascertained to be an exceedingly specialized form of the Lemuroid type, and must be considered to be one of the most extraordinary of the mammalia now inhabiting the globe. (Plate VI., vol. i., p. 278.)
Fossil Quadrumana.
Not much progress has yet been made in tracing back the various forms of Apes and Monkeys to their earliest appearance on the globe; but there have been some interesting recent discoveries, which lead us to hope that the field is not yet exhausted. The following is a summary of what is known as to the early forms of each family:—
Simiidæ.—Two or three species of this family have been found in the Upper Miocene deposits of France and Switzerland. Pliopithecus, of which a species has been found at each locality, was allied to the gibbons (Hylobates), and perhaps to Semnopithecus. A more remarkable form, named Dryopithecus, as large as a man, and having peculiarities of structure which are thought by Gervais and Lartet to indicate a nearer approach to the human form than any existing Ape, has been found in strata of the same age in France.
Semnopithecidæ.—Species of Semnopithecus have been found in the Upper Miocene of Greece, and others in the Siwalik Hills of N. W. India, also of Upper Miocene age. An allied form also occurs in the Miocene of Wurtemburg. Mesopithecus from Greece is somewhat intermediate between Semnopithecus and Macacus.
Remains supposed to be of Semnopithecus, have also occurred in the Pliocene of Montpellier.
Cynopithecidæ.—Macacus has occurred in Pliocene deposits at Grays, Essex; and also in the South of France along with Cercopithecus.
Cebidæ.—In the caves of Brazil remains of the genera Cebus, Mycetes, Callithrix, and Hapale, have been found; as well as an extinct form of larger size—Protopithecus.
Lemuroidea.—A true lemur has recently been discovered in the Eocene of France; and it is supposed to be most nearly allied to the peculiar West African genera, Perodicticus and Arctocebus.
Cænopithecus, from the Swiss Jura, is supposed to have affinities both for the Lemuridæ and the American Cebidæ.