SUBORDER SIMPLICIDENTATA Section SCIUROMORPHA.—In this section the zygomatic arch, which is slender, is chiefly formed by the jugal; the angular part of the mandible arises from the inferior surface of the socket of the lower incisor. Collar bones well developed; tibia and fibula distinct. This section may be divided into 5 families:—(I.) Anomaluridae: arboreal rodents without postorbital processes ; dentition i. p. +, m. 4, and auditory bullae large. Near the root of the tail, on its underside, are a series of imbricated scales, which may be large and pointed (Anomalurus), or small and ridge-like (Idiurus and Zenkerella). A cutaneous parachute-like expansion, supported by a cartilaginous spur from the elbow, connects the limbs and tail in genera Anomalurus and Idiurus; it is absent in Zenkerella. This family is entirely confined to Africa where the various species are distributed over the greater part of Equatorial Africa from Liberia to Kenya Colony, as far south as Northern Rhodesia. The genus Anomalurus, the large Scaly-tailed Flying Squirrels. contains a large number of handsomely coloured species. The genus Idiurus contains the Pigmy Scaly-tails which are much smaller than the species of Amomalurus, with less bushy tails and brownish grey in colour ; the three known species are found in West and Central Africa, from the Cameroons to the Ituri Forest, E. Congo. The Flightless Scaly-tail (Z. insignis) hails from the Cameroons.
Rhodesia ; cheek teeth species numerous, usually greyish above, white or orange-coloured below. (3) Myrsilus, one species, M.
aubinii, the West African Giant Squirrel (length of body 9 inches). Cheek teeth -. (4) Funisciuris, the Side-striped Squir rels, distinguished by their more elongated skulls, teeth highly specialized, cheek teeth confined to the West African Forest Zone. (5) Paraxerus, closely allied to Funisciurus, skull less elon gated, teeth less specialized; confined to the Ethiopian Region. (6) Tamiscus, closely related to Paraxerus, distinguished by the presence of two or four black stripes running down the back, with light coloured lines between them. These Dwarf Striped Squirrels occur in the East Congo, Uganda, and the Sudan. (7) Myosciurus, a genus containing one very small species M. minutus (head and body 6o mm.) not any larger than the Common Mouse; found only in the Cameroons and Gaboon. (8) Protoxerus, Afri can Giant Squirrels, found in Fernando Po, the Gold Coast east wards through the Congo to Kenya Colony, being more or less equatorial in distribution. These squirrels are very large (head and body II inches) and heavily built. (9) Epixerus, the Red faced Giant Squirrels, of the Gaboon west to Ashanti; like Protoxcrus but with the skull elongated. ( o) Atlantoxerus, the N. African Ground Squirrel, A. getulus, is a large form (head and body 8 inches) with a broad, depressed skull; cheek-teeth I, mo lars simple in structure. Hair, as in all ground squirrels, harsh and scanty ; back brownish with four dark stripes. (II) Xerus, the East African Ground Squirrels, reddish coloured species with unstriped bodies ; skull with convex profile, and cheek-teeth 4-, found in Abyssinia, Somaliland, and Kenya Colony. (12) Geo sciurus, contains but a single species, G. capensis, the South Afri can Ground Squirrel, rather larger than the East African species, with a well-marked light flank-stripe. (r3) Euxerus, the Equatorial Ground Squirrels, differ from the other members of the group in having long narrow skulls and narrow zygomata ; cheek-teeth The species are found throughout the West can Forest region and spread eastward to the Sudan and East Africa.