Under this family heading are included the whole of the remaining members of the Sub-order. They all possess certain main characters in common; but on account of the presence or {23}absence of certain subordinate features in some of the groups, the family has been further subdivided into four sub-families. The more important characters which they have in common are the thick woolly fur, the Dog- or Fox-like snout and nostrils--a character obviously distinguishing them from the bulk of the Monkeys, in which the nose forms a subsidiary feature, and is not the main part of the face,--and especially the number and form of their teeth. In the centre of the upper jaw there is always a toothless gap, or _diastema_, on each side of which the teeth are arranged according to the following formula: I2/2, C1/1, P3/3, M3/3 = 36. Among the Endrinas, however, the formula is I2/2, C1/(1 or 0), P2/2, M3/3 = 32 or 30 in number. In the upper jaw the incisors are small and perpendicular; but in the lower, where they are long and narrow, they protrude horizontally in front, and then follow, parallel and close to them, the somewhat thicker canines, the six teeth together forming a comb-like series. The anterior pre-molar is always vertically longer than the others, and assumes the form and function of the canines in other animals. In some genera (e.g., _Propithecus_), Milne-Edwards has observed that in the young animal the cerebellum is more overlapped by the cerebrum (or main brain) than it is later in life; and Dr. Major believes that the _Lemuridæ_ are highly specialised members of the Sub-order, developed from ancient types which were not unlike the American Monkeys of the family _Cebidæ_. The Typical Lemurs are arranged in the following four sub-divisions: The Pottos and Slow-paced Lemurs (_Lorisinæ_); the Galagos and Mouse-Lemurs (_Galaginæ_); the True Lemurs (_Lemurinæ_); and the Endrinas (_Indrisinæ_). {24}THE SLOW-LEMURS. SUB-FAMILY I. LORISINÆ. This Sub-family has been constituted to receive a small number of Lemurs, which, although occupying limited areas in two widely separated continents--one genus being African and the others Asiatic--present certain characters in common. They are recognised by having soft woolly fur, a triangular head and pointed face, very large and staring eyes, set close together, while their ears are naked along their margin. Their fore- and hind-limbs are nearly equal. In the Asiatic genera the index finger is very small, while in the African it is quite rudimentary and nail-less. In both groups the thumb diverges widely from the other fingers, and the great toe is directed backwards, but the ankle-bones of the foot are not elongated. The tail is either so short as to be quite concealed in the fur, or is less than one-third of the length of the body. [Illustration: Fig. 6. Front Teeth of Perodicticus, Nycticebus and Loris, after Mivart (P. Z. S., 1864, p. 631).]