L. mergulus, is about the size of Mus rattus; it has webbed toes and a powerful laterally-compressed tail. Clavicles are present, which is not the case with Potamogale.
Oryzoryctes is a Mole-like Centetid. It has fossorial fore-limbs, but a fairly long tail. This genus is furry like the last two. It is said to burrow in the rice-fields and to do much harm. The teeth are forty in number, three incisors and three molars in each half of each jaw.
Fam. 4. Potamogalidae.—This family contains two genera, Potamogale and Geogale.
Potamogale velox is a West African animal, which though an Insectivore has the habits of an Otter. It is "somewhat larger than a stoat." The upper surface of the body is dark brown, the belly brownish yellow. It has a flat head and a long tail like the Stoat, but the tail is laterally compressed and very thick. The eyes are very small; the nostril has valves. The toes are not webbed; but the second and third toes are united for the whole length of their first phalanges. Along the outer side of the foot is a thin extension of the integument. In swimming the feet are drawn up along the body, hence webbing would be of no use; but the thin flattening prevents the edge of the foot from acting as a hindrance to the motion of the animal. M. du Chaillu describes it as catching fish, which it pursues with extreme rapidity in the clear mountain streams it frequents; but Dr. Dobson, remarking that no stomachs have been examined, thinks that water insects are more probably its prey. It is not known whether the animal possesses a caecum. The tooth formula[1] is I 3/3 C 1/1 Pm 3/3 M 3/3. The animal is exceptional among the Insectivora in having no clavicles.[2] There are sixteen ribs; there is no zygomatic arch, and the pterygoids converge posteriorly.
Geogale, with one species, G. aurita, is a small representative of this family from Madagascar. It has only thirty-four teeth. When better known it may be necessary, thinks Mr. Lydekker, to make this animal the type of a separate family. The tibia and fibula are distinct, not confluent with one another as in Potamogale.
Fam. 5. Solenodontidae.—This family contains but a single genus.
