SKULL OF
GOLDEN MOLE.
DENTITION OF GOLDEN MOLE.
These animals have a cylindrical body, clothed with a fine, close fur, usually exhibiting a metallic lustre which has been compared to that presented by the feathers of some of the most brilliant birds. They have a conical head, short limbs, a very short, almost rudimentary tail, minute eyes, actually covered by the skin, and no external ears. From the form of the body, the texture of the hair, and the structure of the limbs, they are as evidently organised for burrowing underground as the Moles, with which they have generally been associated; but the structure of the mechanism by which their burrowing is effected is so different that, taken in conjunction with certain other characters, it has led modern zoologists to regard the Golden Moles, notwithstanding their scanty numbers, as constituting a perfectly distinct family of the Insectivora.
The skull is shorter, more wedge-shaped, and more elevated at the back than in the true Moles, and the premaxillary bones form a process which is curiously turned outwards (see [figure, p. 365]), but this does not run to the extremity of the snout, which is supported by cartilages. The dentition is very peculiar. The total number of teeth is either thirty-six or forty, one species having two molars less in each jaw than the others; the front upper pair are large and pyramidal in form, presenting some resemblance to the corresponding teeth in the Desmans; these are followed on each side by three minute teeth, and these again by five or six true molars, of prismatic form. In the lower jaw there are two pairs of front teeth, followed on each side by three small pointed teeth (premolars), and by four or five true molars.
STERNUM OF
GOLDEN MOLE.
FORE-FOOT OF
GOLDEN MOLE.
(After Owen.)
The structure of the anterior limb, and of the parts which support it, is peculiar and characteristic, differing materially from that which obtains in the true Moles. In the sternum there are seven similar pieces, which receive the extremities of ribs, and behind these a semi-cartilaginous piece, called the ensiform (or sword-like) appendage. In front of the rib-receiving pieces is a large bone (the manubrium), excavated on each side behind to receive the ends of the collar-bones, and furnished along its lower surface with a ridge serving for the attachment of a part of the powerful muscles by which the fore limbs are moved. The form of this part is very different from that of the corresponding piece in the Mole (see [p. 368]). The form and mode of articulation of the collar-bones (clavicles) is also very different. In the True Moles the clavicle is a short, thick bone, almost resembling the vertebra of a fish; in the Golden Moles it is a longer and more slender bone, of ordinary form, and articulated after an ordinary fashion, both with the sternum and the shoulder-blade. The latter bone is larger than in the Mole, and has a very strong spine, which projects far beyond the articulation of the humerus (arm-bone). The humerus itself is a more slender bone than in the Mole, and more of the ordinary form, although it has a very strong tuberosity near the lower extremity; and one of the carpal bones (the pisiform) is most unusually developed, passing up alongside of the bones of the fore-arm (radius and ulna), until it reaches the humerus. The fore foot is quite different in its construction from that of the Mole. The latter consists of five toes, armed with large flat claws, and forms a shovel-like organ, turned outwards in a peculiar manner. The fore foot of the Golden Mole has only four digits, of which the inner and outer ones (I. and IV. [in figure]) are small, while the second and third toes (II. and III.) are large and armed with very large claws; the claw-joint of the third, especially, being of enormous size, and cleft nearly to its base. With this powerful instrument the Golden Mole digs his way very readily through the ground, using his hind feet, which have five toes, and much resemble those of ordinary Moles, to push him forward in his burrows.