lower down than in the human subject, a circumstance which causes the leg to be permanently kept in a semiflexed condition.

The 'gastrocnemius,' fig. 11, 6, is relatively less carneous than in Man: the 'solæus' is slender and feeble: but the plantaris,' fig. 12, 13, is remarkably developed; it arises from the fossa above the external femoral condyle: its tendon, 15, is continued downward, and runs over the extremity of the os calcis, where it is enclosed in a sheath; passing on from this point, it divides, 18, to be inserted upon each side of the posterior surface of the proximal phalanx towards its inferior extremity, here giving passage between its two insertions to the tendon of the long flexor of the toe, which it serves to bind down closely to the pastern when the fetlock joint is bent, thus seeming to perform the functions both of the plantaris' and of the short flexor of the toes.

The tibialis anticus,' fig. 12, 37, is implanted into the anterior surface of the base of the metatarsal, so as to be an extensor of that portion of the foot. The tibialis posticus' is seen at 25 and 26, fig. 12. The 'popliteus,' ib. 23, is a powerful muscle. The three 'peronei' are represented by a single muscle, the tendon of which becomes conjoined with that of the long extensor of the digit, with which, when in action, it co-operates. The flexor muscles are reduced to a state of extreme simplicity; the short flexor communis is wanting; the plantaris,' as described above, has a double insertion into the base of the great pastern bone, and presents a similar disposition to that of the flexor perforatus in digitate quadrupeds, while the 'flexor communis longus perforans,' fig. 12, 28, here serving a single tendon, 29, appropriated to the solitary toe, passes on as usual to be inserted into the last phalanx, 30, 31. The homologue of the 'flexor longus hallucis' exists in the Horse, notwithstanding the absence of the hallux; but, instead of its usual destination, it here becomes affixed to the tendon of the flexor communis perforans, to which it forms a powerful auxiliary.

The extensor communis,' fig. 11, 21, terminates in a single tendon, 23, which is inserted into the dorsum of the last phalanx of the foot: it receives, however, in its course, a few fleshy fibres, w, derived from the metacarpal and representing the extensor brevis' of unguiculate quadrupeds.

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In fig. 14, showing the chief ligaments of the hind limb, are represented the iliacus internus,' i, k, l, and the epicotyloideus,' a, a small and peculiar muscle, which arises by a flat tendon, b, from above the origin of the rectus cruris, d, and is inserted at the fore and outer part of the neck of the femur, c, below the head;

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its fibres are attached to the capsular ligament. 21 is the rotulocondylar ligament;' 22 the rotular ligament;' 23 the external rotular ligament;' 10 the condylo-fibular ligament;' 15 the external semilunar cartilage;' 25 the calcaneal ligament;' 26, 26, the 'external lateral ligaments' of the ankle and succeeding joints; 27 the ant-oblique ligament;' 28 the ligament from the outer splint-bone (metatarsal IV) to the sesamoid behind the metacarpophalangial joint: 38 and 39 are cartilages of the hoof.

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Muscles of the hyoid arch. The sterno-hyoideus' and the 'sterno-thyroideus' form a single muscle, which divides to be inserted into both the larynx and os hyoides. The omohyoideus,' fig. 11, a, is a very strong muscle. The 'stylohyoideus' furnishes a sheath to the longer portion of the digastricus, and extends from the furcate extremity of the stylohyal to the base of the thyrohyal. There is also a cerato-hyoideus' extending between the thyrohyal and the thyroid cartilage. The 'paroccipito-styloideus' is a short thick muscle, derived from the paroccipital, whence it descends toward the angle of the stylohyal, into which it is inserted, above the origin of the stylohyoideus.

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Facial muscles. The occipito-frontalis' has the usual origin from the posterior part of the cranium, whence, running forward, it covers the skull with its tendinous aponeurosis, and, in front, spreads in muscular slips upon the forehead, some of which, fig. 11, 12, extend downward, to spread over those of the orbicularis palpebrarum.

Situated upon the outer side of the orbit there is another descending slip of muscle derived from the lateral cartilage of the ear, which, by elevating the external canthus of the eye, contributes to the expression of that organ.

The 'levator anguli oris,' fig. 11, n, is inserted into the upper lip and margin of the nostril: it has two origins, derived from the surface of the superior maxillary bone, between which the lateral dilator of the nostril and upper lip passes to its destination. The ' zygomaticus' is a depressor of the external angle of the eye, as well as an elevator of the corner of the mouth, its fibres being intermixed with those of the orbicularis palpebrarum, as well as of the orbicularis oris.

The long dilator of the nostril, and elevator of the upper lip' arises at a little distance below the inferior margin of the orbit; and, passing between the two origins of the levator anguli oris, terminates in a tendon, which becomes connected with that of the opposite side, and then spreads out in front of the upper lip.

From the tendon of the last muscle arises the anterior dilator of the nostril,' fig. 11, t, which, acting upon the interior nasal cartilage, powerfully expands the aperture of the nose. The 'orbicularis oris,' fig. 11, o, the 'levator labii superioris,' the 'elevator of the chin,'

15

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The longitudinal section of the huge finger that forms the foot or 'hoof' of the horse, fig. 15, shows the structure of the three phalanges-proximal 1, middle 2, and distal or ungual 4, with that of the sesamoid, or nut-bone 3, adding to the lever-power of the division of the tendon, 7, of the flexor profundus, going to the last phalanx: the insertion of the tendon of the 'flexor sublimis,' 6, and that of the tendon of the common extensor,' 5, are also shown. The hoof-box of the ungual phalanx is denser at its periphery, 12, than at its base, 10, but is not continuous over either surface; the former part is the wall,' the latter the floor' of the horny or 'insensible' hoof. The wall, or external wall,' has the form of a hollow cone obliquely truncate above, so that it is highest in front, 12, becoming vertical, and lower as it extends backward, losing density, degenerating partly into the elastic tissue, 9, but being mainly inflected inward, toward the centre of the sole, where it blends with the horny floor,' and forms the internal wall:' this supports the superincumbent softer elastic tissue, and partly that called the frog,' fig. 16, 3, for which a triangular space is left between the inflected parts of the internal wall.' posterior part of the periphery and of the floor of the hoof' is left uncovered by the horny box, which is accordingly free for a certain degree of elastic expansion and contraction, especially posteriorly. The inner surface of the wall' is produced into a

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Thus the

number of subvertical lamellæ, fig. 17, 3, with which interdigitate corresponding lamellæ, ib. 17, from the periosteum of the ungual phalanx: the first are called the horny lamellæ,' the second the vascular' or sensitive lamellæ.' At the interspace between the inflected parts or prongs of the wall' projects the mass of elastic subcorneous tissue called by the French farriers 'fourche,' and misnamed by the English frog.' In the horizontal section of the hoof, fig. 16, in which a part, 2, is reflected back, the 'frog,' 3, is seen to extend to the centre of the sole: its exposed outer surface is the hardest and most horny; but this tissue is not so thick

12

16

Horse. 11".

as

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some farriers, misapplying the paring-knife, suppose: it gradually passes into elastic tissue: it is impressed at its middle part by the 'cleft of the frog,' and is reflected upon the internal wall.' In fig. 16, 2, 6, is the section of the wall;" 3, the upper surface of the frog;' 4, 4, are the parts of the 'wall' called the heels;' 5, parts of the sole called the bars; 7-11 indicate the boundaries of the space lodging the frog; 12, are the vascular lamellæ.' The horny matter of the sole possesses more elasticity than that of the wall: the sole is slightly concave toward 12 the ground, abutting by its lower circumference against the wall: it is cleft to its centre by the triangular space through which the frog projects.

In fig. 17, 1 is the skin reflected; 2, soft elastic tissue, with oil, forming a cushion behind the metacarpo-phalangial joint; 3, wall' of the hoof turned back, showing the horny lamella; 4, section of front part of the 'wall;' 5, 6, ligamentous parts of metacarpo-phalangial joint; 7, tendon of common extensor;' 8, 9, 10, those of the deep and superficial flexors; 15, expansion of the great anterior cartilage of the hoof; 16, the coronary frog-band' reflected; 17, the vascular lamella;' 18, elastic portion of the 'frog;' the coronary venous plexus' is shown at 5.

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In the Indian Rhinoceros the panniculus carnosus is more discontinuous than in other Perissodactyles, but where it exists is of unusual thickness. One sheet at the side of the thorax sends its fascia into

the interstice of the dermal fold in front of the fore limbs. A similar portion behind is inserted into the posterior fold of the skin, suggesting that such permanent folds served the purpose of affording a firmer insertion to the aponeuroses of the cutaneous muscles than a plane surface could have done. Two sheets of panniculus rise, broad and thick, one on each side of the anterior part of the abdomen from the superficial fascia, and, passing backward, terminate in aponeuroses covering knee-joint. As the patellæ are higher than the line of the abdomen, in the erect

position of the animal, the preceding muscles afford additional support to that bulky part, some of the weight thus being transferred to the hind-legs, which, reciprocally, are by these muscles drawn forward in locomotion.'

§ 198. Muscles of Artiodactyla.-In the Ruminant division of the Artiodactyle Ungulates the panniculus carnosus' is better developed than in the non-ruminant group, e. g. the hog and the hippopotamus. The fixed points, from which, in the ox, the well-developed sheets of dermal carneous fibres act on the skin are the scapula, mandible, ilium, pubis, and patella: a

1 v". p. 36.