adaptation to a digging life is brought about in quite a different way from that of the true Moles (Talpa). In the latter the fore-limbs are changed in position by the elongation of the manubrium sterni, carrying with it the clavicles, which are extraordinarily shortened (Fig. 251). In Chrysochloris, on the other hand, the same need (i.e. that the limbs project as little as possible from the sides of the body, while the length of the limbs is retained, and the leverage of the muscles unaffected) is provided for by a hollowing out of the walls of the thorax, the ribs and the sternum being here convex inwards. The sternum and the clavicles are not modified. The tibia and fibula are ankylosed below. In the manus, moreover, there are but four digits, of which the two middle ones are greatly enlarged. In the Moles there are five fingers, and all are enlarged; there is, too, a great radial sesamoid bone, which is as good as a sixth finger (which, indeed, it is considered to be, in common with similar structures in other animals, by some anatomists). The foot has only four toes.

Fig. 249.—Golden Mole. Chrysochloris trevelyani. A, Lower surface of fore-foot. × ½. (After Günther.)

Fam. 7. Macroscelidae.[[379]]—This family contains three genera, all of them African in range, and mainly Ethiopian.

Macroscelides, the Elephant Shrews, are jumping creatures of Shrew-like appearance, combined with a Marsupial look. Both radius and ulna, and tibia and fibula, are ankylosed. There

are five fingers and toes. There is a caecum as in but few Insectivores. The tooth formula, as revised by Thomas,[[380]] is I 3/3 C 1/1 Pm 4/4 M 2/(2 or 3), the total number being thus forty or forty-two. There are several species of this genus.

Fig. 250.—Rhynchocyon chrysopygus. × ¼. (After Günther.)

Rhynchocyon and Petrodromus differ from Macroscelides in not having such long hind-legs. The dental formula of the first is I (1 or 0)/3 C 1/1 Pm 4/4 M 2/2 = 34 or 36, of the latter I 3/3 C 1/1 Pm 4/4 M 2/2 = 40. In Petrodromus the toes are reduced to four; in Rhynchocyon there are only four digits in the manus as well as in the pes. This animal, as its name implies, has a longish proboscis, which can be bent, and is really very like a miniature Elephant's trunk, and also like that of the Desman (Myogale). It has thirteen pairs of ribs, and a well-developed caecum. Dr. Günther has pointed out that in Petrodromus tetradactylus the hairs of the lower part of the tail are stiff elastic bristles 5 mm. long, with a swelling at the free tip. The use of this singular modification is not at all apparent. Pseudorhynchocyon, of European Oligocene, is believed to be related to this family.

Fig. 251.—Sternum and sternal ribs of the Common Mole (Talpa europaea), with the clavicles (cl) and humeri (H); M, Manubrium sterni. Nat. size. (From Flower's Osteology.) Fig. 252.—Bones of fore-arm and manus of Mole (Talpa europaea). × 2. C, Cuneiform; ce, centrale; l, lunar; m, magnum; p, pisiform; R, radius; rs, radial sesamoid (falciform); s, scaphoid; td, trapezoid; tm, trapezium; U, ulna; u, unciform; I-V, the digits. (From Flower's Osteology.)