The bones of the forearm (fig. 4 4 2, d,c) in the extraordinary animal which offers so many de viations from typical structure, the mole, are no less remarkable than those of the shoulder. The ulna is very broad and much flattened ; its superior extremity is enlarged transversely, the anterior surface concave, the posterior convex. The radius is separated by a considerable in terval from the ulna throughout their length, and the two bones are only united at the upper extremity by a capsular ligament. But the articular surfaces of the two bones are flat, and the head of the radius is prolonged into a hook like process, forming a sort of radial olecranon, so that rotation is impossible. The carpal bones (fig.444)consist of two series of five in each, and an additional bone of a very peculiar construc tion. This is a large sickle-shaped or falciform bone, having the convex margin outwards ; it extends from the carpal extremity of the radius to the first metacarpal bone. It is this bone which gives the great breadth to the hand, which is so important to this animal in its peculiar mode of life.
The phalanges of the fingers are very short, and covered by the integument in such a manner as to appear to belong to the meta carpal portion of the hand ; and it is only the long sharp nails which extend beyond the skin, and are externally visible.
The position then of the anterior extremity of the animal is this : the humerus is so placed that the inferior or distal extremity is the most raised, so that the fore-arm is kept in a state between pronation and supination, the elbow raised, the radius and the thumb placed down wards, and the palm of the hand directed out wards. When to this we add the peculiar flexion of the last phalanx of the fingers with the enormous nails, we have a fossorial struc ture not equalled by any other in the whole of the vertebrated animals, and only imitated by the no less remarkable anomaly amongst insects, the Gryllotalpa or mole-cricket.
In Chrysochloris the third and fourth fingers are united by one large powerful nail, and are developed to an extraordinary size (fig. 445), the fifth finger being reduced to a minute diment; and the carpal bones are placed in an abrupt curve, so that the outer side of the fifth finger approaches the first. The os pisiforme as sumes also a peculiar development, being very much elongated, rises in the direction of the forearm, and is actually articulated with the internal condyle of the humerus.
The pelvis in the Talpida and Soricida is extremely long. The ilia are narrow and pointed at the anterior part. In the last-named family, the pubis and the ischium are especially long and narrow. In Chrysochloris, on the contrary, the ischium is very broad.
The femur offers but few and unimportant particularities amongst the Insectivora, unless it be that there is in the mole and Chrysochloris a sort of third trochanter; a process which is also found in some of the lower Quadrumana, and in some other of the Mammifera. The fibula is united to the tibia for nearly the inferior third of their length, in the 2'alpidee, the Soricidee, and the Erinaceclee. In the mole this union is to a greater extent than perhaps in any other animal of the 1\Iammiferous class.
The binder feet in the whole of this order are plantigrade. In the mole, as Daubenton and Meckel have observed, there is an addi tional tarsal bone, to those which are ordinarily found. It is of considerable size, and seems to answer to the falciform bone of the anterior extremities already described. It is of an uniform shape, of considerable size, and is arti culated between the scaphoid and the first cuneiform bone, and extends forwards along the first metatarsal.
II. Muscles.—The extraordinary develope ment of the bones of the anterior extremity in the mole, will, of course, be associated with a no less remarkable structure in the muscles of the same part; and the known habits of the animal will account equally for the necessity of such a structure in both. I give a figure of the muscles of the anterior extremity and of the anterior part of the trunk from Carus. ( Fig. 446.) The cervical portion of the samba magnus is simple, excessively thick and swelling, and is attached only to the posterior vertebrae. The trapczius consists only of two bundles of fleshy fibres, which arise from the lumbar ver tebrae, and are inserted into the posterior ex tremities of the long and narrow scapula:; and as these fasciculi are nearly parallel, their action would be rather to separate than to ap proximate the posterior parts of these bones, were it not for a strong transverse ligament which holds them together. Their application consists in moving the anterior part of the body upwards. The scapular attachments of the rhomboacus are principally to this transverse ligament of the two scapulas, and as it is in serted into a sort of ossified modification of a cervical ligament, its office consists in raising the head with great force. The levator scapula is wanting; its existence would be obviously useless. The pectorals miner is very slender ; it is attached to the anterior parts of the first ribs, and to the ligament, already mentioned, which joins the clavicle to the scapula. There are also two muscles arising from the anterior part of the sternum, and inserted into the large head of the clavicles.