sillimanite, but kyanite appears also in hornfelses, especially in those which have a schistose character. The andalusite may be pink and is then often pleochroic in thin sections, or it may be white with the cross-shaped dark enclosures of the matrix which are characteristic of chiastolite. Sillimanite usually forms exceedingly minute needles embedded in quartz. In the rocks of this group cordierite also occurs, not rarely, and may have the outlines of imperfect hexagonal prisms which are divided up into six sectors when seen in polarized light. In biotite hornfelses a faint striping may indicate the original bedding of the unaltered rock and corresponds to small changes in the nature of the sediment deposited. More commonly there is a distinct spotting, visible on the surfaces of the hand specimens. The spots are round or elliptical, and may be paler or darker than the rest of the rock. In some cases they are rich in graphite or carbonaceous matters; in others they are full of brown mica; some spots consist of rather coarser grains of quartz than occur in the matrix. The frequency with which this feature reappears in the less altered slates and hornfelses is rather remarkable, especially as it seems certain that the spots are not always of the same nature or origin. Tourmaline hornfelses" are found sometimes near the margins of tourmaline granites; they are black with small needles of schorl which under the microscope are dark brown and richly pleochroic. As the tourmaline contains boron there must have been some permeation of vapours from the granite into the sediments. Rocks of this group are often seen in the Cornish tin-mining districts, especially near the lodes.

A second great group of hornfelses are the calc-silicate-hornfelses which arise from the thermal alteration of impure limestones. The purer beds recrystallize as marbles, but where there has been originally an admixture of sand or clay lime-bearing silicates are formed, such as diopside, epidote, garnet, sphene, vesuvianite, scapolite; with these phlogopite, various felspars, pyrites, quartz and actinolite often occur. These rocks are finegrained, and though often banded are tough and much harder than the original limestones. They are excessively variable in their mineralogical composition, and very often alternate in thin seams with biotite hornfels and indurated quartzites. When perfused with boric and fluoric vapours from the granite they may contain much axinite, fluorite and datolite, but the aluminous silicates (andalusite, &c.) are absent from these rocks. From diabases, basalts, andesites and other igneous rocks a third type of hornfels is produced. They consist essentially of felspar with hornblende (generally of brown colour) and pale pyroxene. Sphene, biotite and iron oxides are the other common constituents, but these rocks show much variety of composition and structure. Where the original mass was decomposed and contained calcite, zeolites, chlorite and other secondary minerals either in veins or in cavities, there are usually rounded areas or irregular streaks containing a suite of new minerals, which may resemble those of the calc silicate hornfelses above described. The original porphyritic, fluidal, vesicular or fragmental structures of the igneous rock are clearly visible in the less advanced stages of hornfelsing, but become less evident as the alteration progresses.

In some districts hornfelsed rocks occur which have acquired a schistose structure through shearing, and these form transitions to schists and gneisses which contain the same minerals as the hornfelses, but have a schistose instead of a hornfels structure. Among these may be mentioned cordierite and sillimanite gneisses, andalusite and kyanite mica schists, and those schistose calc silicate rocks which are known as cipolins. That these are sediments which have undergone thermal alteration is generally admitted, but the exact conditions under which they were formed is not always clear. The essential features of hornfelsing are ascribed to the action of heat, pressure and permeating vapours, regenerating a rock mass without the production of fusion (at least on a large scale). It has been argued, however, that often there is extensive chemical change owing to the introduction of matter from the granite into the rocks surrounding it. The formation of new_felspar in the hornfelses_is_pointed out as

evidence of this. While this "felspathization" may have occurred in a few localities, it seems conspicuously absent from others. Most authorities at the present time regard the changes as being purely of a physical and not of a chemical nature. (J. S. F.) HORNING, LETTERS OF, a term in Scots law. Originally in Scotland imprisonment for debt was enforceable only in certain cases, but a custom gradually grew up of taking the debtor's oath to pay. If the debtor broke his oath, he became liable to the discipline of the Church. The civil power, further, stepped in to aid the ecclesiastical, and denounced him as a rebel, imprisoning his person and confiscating his goods. The method declaring a person a rebel was by giving three blasts on a horn and publicly proclaiming the fact; hence the expression, "put to the horn." The subsequent process, the warrant directing a messenger-at-arms to charge the debtor to pay or perform in terms of the letters, was called "letters of horning." This system of execution was simplified by an act of 1837 (Personal Diligence Act), and execution is now usually by diligence (see EXECUTION).

HORNPIPE, originally the name of an instrument no longer in existence, and now the name of an English national dance. The sailors' hornpipe, although the most common, is by no means the only form of the dance, for there is a pretty tune known as the "College Hornpipe," and other specimens of a similar kind might be cited. The composition of hornpipes flourished chiefly in the 18th century, and even Handel did not disdain to use the characteristic rhythm. The hornpipe may be written in or in common time, and is always of a lively. nature.

HORNSEY, a municipal borough in the Hornsey parliamentary' division of Middlesex, England, suburban to London, 6 m. N. of St Paul's Cathedral, on the Great Northern railway. Pop. (1891) 44,523; (1901) 72,056. It is chiefly occupied by small residences of the working classes. The manor, called in the 13th century Haringee (a name which survives as Harringay), belonged from an early date to the see of London, the bishops having a seat here. In 1387 the duke of Gloucester, uncle of Richard II., assembled in Hornsey Park the forces by the display of which he compelled the king to dismiss his minister de la Pole, earl of Suffolk; and in 1483 the park was the scene of the ceremonious reception of Edward V., under the charge of Richard, duke of Gloucester, by Edmund Shaw, lord mayor of London. The parish church of St Mary, Hornsey, retains its Perpendicular tower (c. 1500) and a number of interesting monuments. Finsbury Park, of 120 acres, and other smaller public grounds, are within the borough. Hornsey was incorpor ated in 1903 under a mayor, 10 aldermen and 30 councillors. Area, 2875 acres.

HOROWITZ, ISAIAH (c. 1555-c. 1630), Jewish rabbi and mystic, was born at Prague, and died at Safed, then the home of Jewish Kabbala. His largest work is called Shelah (abbreviated from the initials of the full title Shene luhoth ha-berit, "Two Tables of the Covenant "). This is a compilation of ritual, ethics and mysticism, and had a profound influence on Jewish life. It has been often reprinted, especially in an abbreviated form. 4

For an account of the Jewish mystics at Safed see S. Schecter, Studies in Judaism, series ii. (1908).

HORREUM, the Latin word for a magazine or storehouse for the storage of grain and other produce of the earth, and occasionally for that of agricultural implements. The storehouses of Rome were of the most extensive character, there being no fewer than 290 public horrea at the time of Constantine. They were used for the storage of food and merchandize of all kinds, being part of the great Roman system of providing food for the population, and they were supplied constantly with corn and other provisions from Africa, Spain and elsewhere..

HORROCKS, JEREMIAH (1619-1641), English astronomer, was born in 1619 at Toxteth Park, near Liverpool. His family was poor, and the register of Emmanuel College, Cambridge, testifies to his entry as sizar on the 18th of May 1632. Isolated in his scientific tastes, and painfully straitened in means, he

tion. His university career lasted three years, and on its termination he became a tutor at Toxteth, devoting to astronomical observations his brief intervals of leisure. In 1636 he met with a congenial spirit in William Crabtree, a draper of Broughton, near Manchester; and encouraged by his advice he exchanged the guidance of Philipp von Lansberg, a pretentious but inaccurate Belgian astronomer, for that of Kepler. He now set himself to the revision of the Rudolphine Tables (published by Kepler in 1627), and in the progress of his task became convinced that a transit of Venus overlooked by Kepler would nevertheless occur on the 24th of November (O.S.) 1639. He was at this time curate of Hoole, near Preston, having recently taken orders in the Church of England, although, according to the received accounts, he had not attained the canonical age. The 24th of November falling on a Sunday, his clerical duties threatened fatally to clash with his astronomical observations; he was, however, released just in time to witness the punctual verification of his forecast, and carefully noted the progress of the phenomenon during half an hour before sunset (3.15 to 3.45). This transit of Venus is remarkable as the first ever observed, that of 1631 predicted by Kepler having been invisible in western Europe. Notwithstanding the rude character of the apparatus at his disposal, Horrocks was enabled by his observation of it to introduce some important corrections into the elements of the planet's orbit, and to reduce to its exact value the received estimate of its apparent diameter.

After a year spent at Hoole, he returned to Toxteth, and there, on the eve of a long-promised visit to his friend Crabtree, he died, on the 3rd of January 1641, when only in his twenty second year. To the inventive activity of the discoverer he had already united the patient skill of the observer and the practical sagacity of the experimentalist. Before he was twenty he had afforded a specimen of his powers by an important contribution to the lunar theory. He first brought the revolutions of our satellite within the domain of Kepler's laws, pointing out that her apparent irregularities could be completely accounted for by supposing her to move in an ellipse with a variable eccentricity and directly rotatory major axis, of which the earth occupied one focus. These precise conditions were afterwards demonstrated by Newton to follow necessarily from the law of gravitation.

In his speculations as to the physical cause of the celestial motions, his mind, though not wholly emancipated from the tyranny of gratuitous assumptions, was working steadily towards the light. He clearly perceived the significant analogy between terrestrial gravity and the force exerted in the solar system, and by the ingenious device of a circular pendulum illustrated the composite character of the planetary movements. He also reduced the solar parallax to 14" (less than a quarter of Kepler's estimate), corrected the sun's semi-diameter to 15′ 45′′, recommended decimal notation, and was the first to make tidal observations.

Only a remnant of the papers left by Horrocks was preserved by the care of William Crabtree. After his death (which occurred soon after that of his friend) these were purchased by Dr Worthington, of Cambridge; and from his hands the treatise Venus in sole visa passed into those of Hevelius, and was published by him in 1662 with his own observations on a transit of Mercury. The remaining fragments were, under the directions of the Royal Society, reduced by Dr Wallis to a compact form, with the heading Astronomia Kepleriana defensa et promota, and published with numerous extracts from the letters of Horrocks to Crabtree, and a sketch of the author's life, in a volume entitled Jeremiae Horroccii opera posthuma (London, 1672). A memoir of his life by the Rev. Arundell Blount Whatton, prefixed to a translation of the Venus in sole visa, appeared at London

in 1859.

ii. 253,

For additional particulars, see J. E. Bailey's Palatine Note-Book, iii. 17: Bailey's "Writings of Horrocks and Crabtree (from Notes and Queries, Dec. 2, 1882); Notes and Queries, 3rd series, vol. v., 5th series, vols. ii., iv.; Martin's Biographia philosophica, p. 271 (1764); R. Brickel, Transits of Venus, 16391874 (Preston, 1874); Astronomical Register, xii. 293; Hevelii, Mercurius in sole visus, pp. 116-140; S. Rigaud's Correspondence of Scientific Men; Th. Birch, History of the Royal Society, i. 386, 395. 470; Sir E. Sherburne's Sphere of M. Manilius, p. 92 (1675);

Fragments relative to the Duchy of Lancaster, p. 166 (1817); Liverpool Repository, i. 570 (1826); Phil. Trans. Abridged, ii. 12 (1809); C. Hutton's Phil. and Math. Dictionary (1815); Penny Cyclopaedia (De Morgan); Nature, viii. 117, 137; J. B. J. Delambre, Hist. de l'astronomie moderne, ii. 495; Hist. de l'astronomie au XVIIIe siècle, PP. 28, 61, 74; W. Whewell, Hist. of the Inductive Sciences, i. 331. R. Grant, Hist. of Physical Astronomy, pp. 420, 545; J. Mädler, Geschichte der Himmelskunde, i. 275; M. Marie, Hist. des Sciences, iv. 168, vi. 90; J. C. Houzeau, Bibl. Astr. ii. 167. (A. M. C.)

HORROCKS, JOHN (1768-1804), British cotton manufacturer, was born at Edgeworth, near Bolton, in 1768. His father was the owner of a small quarry, and John Horrocks spent his early days in dressing and polishing millstones. The Lancashire greatly impressed with its future possibilities, and he managed cotton industry was then in its infancy, but Horrocks was to obtain a few spinning-frames which he erected in a corner of his father's offices. For a time he combined cotton-spinning on a very small scale with stone-working, but finally devoted himself entirely to cotton-spinning, working the frames with his own hands, and travelling through the Lancashire manufacturing districts to sell the yarn. His goods obtained a reputation for quality, and his customers increased so rapidly that in 1791 he removed to Preston, where he began to manufacture cotton shirtings and long-cloths in addition to spinning the cotton.yarn. By taking full advantage of the machinery invented for manufacturing textiles, and by rigidly maintaining the quality of his goods, Horrocks rapidly developed his business, and with the erected within a year of his arrival in Preston his first large mill, aid of the capital of a local banker, whom he took into partnership, securing shortly afterwards from the East India Company a monopoly of the manufacture of cottons and muslins for the Indian market. The demand for Horrocks's goods continued to increase, and to cope with the additional work he took first

an elder brother and in 1801 a Mr Whitehead and a Mr Miller

into partnership, the title of the firm being altered to Horrockses, Miller & Co. In 1802 he entered parliament as tory member for Preston. He died in London in 1804 of brain-fever resulting

from over-work.

HORSE (a word common to Teutonic languages in such forms as hors, hros, ros; cf. the Ger. ross), a name properly restricted to the domesticated horse (Equus caballus) and its wild or halfwild representatives, but in a zoological sense used as a general term for all the members of the family Equidae.

SPECIES

The distinctive characteristics of the family, and its position in the zoological system, are given in the articles EQUIDAE and PERISSODACTYLA. Here attention is concentrated on the leading features of the horse as contrasted with the other members of the same family, and subsequently on the anatomical structure of the former animal. The evolution of the existing representatives of the family from primitive extinct animals is summarized in the article EQUIDAE.

Horse, Wild Horse, Pony.-The horse (Equus caballus) is distinguished from the others by the long hairs of the tail being more abundant and growing quite or nearly from the base as well as the end and sides, and also by possessing a small bare callosity on the inner side of the hind leg, just below the "hock" or heel joint, in addition to the one on the inner side of the fore-arm above the carpus or "knee," common to all the genus. The mane is also longer and more flowing, and the ears are shorter, the limbs longer, and the head smaller.

Though existing horses are usually not marked in any definite manner, or only irregularly dappled, or spotted with light surrounded by a darker ring, many examples are met with showing a dark median dorsal streak like that found in all the other members of the genus, and even with dark stripes on the shoulders and legs.

Two distinct types of horse, in many instances largely modified by interbreeding, appear to exist. (1) The northern, or dun type, represented by the dun ponies of Norway (Equus caballus typicus), the closely allied Celtic pony (E. c.celticus) of Iceland, the

Hebrides, &c., and the wild pony of Mongolia (E. c. przewalskii), with which the now extinct tarpan of the Russian steppes appears to have been identical. The prevalent colour is yellowdun, with dark brown or black mane, tail and legs; in the wild forms the muzzle is often white and the root of the tail shorthaired; while the head is relatively large and heavy. No depression exists in the skull in front of the eye. Most of the ordinary horses of N.W. Europe are descended from the dun type, with more or less admixture of Barb blood. (2) The southern, or Barb type, represented by Barbs, Arabs, thoroughbreds, &c. (E. c. asiaticus or libycus), in which the typical colour is bay with black "points" and often a white star on the forehead, and the mane and tail are long and full. The skull generally shows a slight depression in front of the socket of the eye, which, although now serving as the attachment for the muscle running to the nostril, may represent the face-gland of the extinct Hipparion. Many of the dark-coloured horses of Europe have Barb or Arab blood in their veins, this being markedly the case with the Old English black or Shire horse, the skull of which shows a distinct depression in front of the eye-socket. This depression is still more marked in the extinct Indian E. sivalensis, which may have been the ancestral form.

In Europe wild horses were abundant in the prehistoric Neolithic or polished-stone period. Judging from the quantity of their remains found associated with those of the men of that time, the chase of these animals must have been among man's chief occupations, and horses must have furnished him with one of his most important food-supplies. The characters of the bones preserved, and certain rude but graphic representations carved on bones or reindeers' antlers, enable us to know that they were rather small in size and heavy in build, with large heads and rough shaggy manes and tails, much like, in fact, the recently extinct tarpans or wild horses of the steppes of the south of Russia, and the still-surviving Mongolian wild pony

or

"Przewalski's horse." These horses were domesticated by the inhabitants of Europe before the dawn of history. Horses are now diffused by the agency of man throughout almost the whole of the inhabited parts of the globe, and the great modifications they have undergone in consequence of domestication, crossing, and selective breeding are well exemplified by comparing such extreme forms as the Shetland pony, dwarfed by uncongenial climate, the thoroughbred racer, and the London dray-horse. In Australia, as in America, horses imported by European settlers have escaped into unreclaimed lands and multiplied to a prodigious extent, roaming in vast herds over the wide and uncultivated plains.

Ass, Zebra, Quagga.-The next group is formed by the Asiatic wild asses, or kiangs and onagers, as they might well be called, in order to distinguish them from the wild asses of Africa. These asses have moderate ears, the tail rather long, and the back-stripe dark brown and running from head to tail. On the neck and withers this stripe is formed by the mane. There are two species of Asiatic wild ass, with several varieties. The first and largest has two races, the chigetai (Equus hemionus) of Mongolia, and the kiang (E. h. kiang) of Tibet, which is a redder animal. The onager (E. onager), of which there are several races, is smaller, with a broader dorsal stripe, bordered with white; the colour varying from sandy to greyish. This species ranges from Baluchistan and N.W. India to Persia, Syria and Arabia. These asses inhabit desert plains or open table-land; the kiang dwelling at elevations of about 14,000 ft. They are generally found in herds of from twenty to forty, although occasionally in larger numbers. All are fleet, and traverse rough ground with speed. On the lowlands they feed on dry grasses, and in Tibet on small woody plants. In India and Persia they are difficult to approach, although this is not the case in Tibet. Their sandy or chestnut colouring assimilates them to the horse, and separates them widely from the African wild asses, which are grey. The kiang has also larger and more horse-like hoofs, and the tail is haired higher up, thus approximating to Equus caballus przewalskii.

Among the striped species, or zebras and quaggas of Africa,

the large Grévy's zebra (Equus grevyi) of Somaliland and Abyssinia stands apart from the rest by the number and narrowness of its stripes, which have an altogether peculiar arrangement on the hind-quarters, the small size of the callosities on the fore-legs, the mane extending on to the withers and enormous rounded ears, thickly haired internally. The large size of the ears and the narrow stripes are in some degree at any rate adaptations to a life on scrub-clad plains.

Next comes the closely allied species with small pointed ears, of which the true quagga (E. quagga) of South Africa is now extinct. This animal has the dark stripes limited to the head, neck and shoulders, upon a brown ground. In the typical form, now also extinct, of the bonte-quagga, dauw, or Burchell's zebra (E. burchelli), the ground-colour is white, and the stripes cover the body and upper part of the limbs. This was the commonest species in the great plains of South Africa, where it roamed in large herds, often in company with the quagga and numerous antelopes. The species ranges from the Orange river to the confines of Abyssinia, but its more northern representatives show a gradual increase in the striping of the legs, culminating in the north-east African E. burchelli granti, in which the stripes extend to the hoofs. The markings, too, are alternately black and white, in place of brown and creamy, with intermediate "shadow stripes," as in the southern races.

Lastly, there is the true or mountain zebra (E. zebra), typically from the mountain ranges of Cape Colony, where it is now specially protected, but represented by E. zebra penricei in south-west Africa. In its relatively long ears and general build it approaches the African wild asses, from which it chiefly differs by the striping (which is markedly different from that of the quagga-group) and the reversal of the direction of the hairs along the spine.

The African wild ass (E. asinus) is the parent of the domesticated breed, and is a long-eared grey animal, with no forelock, and either a shoulder-stripe or dark barrings on the legs. There are two races, of which the Nubian E. a. africanus is the smaller, and has a continuous dorsal stripe and a shoulder-stripe but no bars on the legs. The Somali race (E. a somaliensis), on the other hand, is a larger and greyer animal, with an interrupted dorsal and no shoulder-stripe, but distinct leg-barrings.

Hybrids.-There are thus eight modifications of the horse-type at present existing, sufficiently distinct to be reckoned as species by most zoologists, and easily recognizable by their external characters. They are, however, all so closely allied that each will, at least in a state of domestication or captivity, breed with any of the others. Cases of fertile union are recorded between the horse and the quagga, the horse and the bonte-quagga or Burchell's zebra, the horse and the onager and kiang or Asiatic wild asses, the common ass and the zebra, the ass and bontequagga, the ass and the onager, the onager and the zebra, and the onager and the bonte-quagga. The two species which are farthest removed in structure, the horse and the ass, produce, as is well known, hybrids or mules, which in certain qualities useful to man excel both their progenitors, and in some countries and for certain kinds of work are in greater requisition than either. Although occasional more or less doubtful instances have been recorded of female mules breeding with the males of one or other of the pure species, it is more than doubtful if any case has occurred of their breeding inter se, although the opportunities of doing so must have been great, as mules have been reared in immense numbers for at least several thousands of years. We may therefore consider it settled that the different species of the group are now in that degree of physiological differentiation which enables them to produce offspring with each other, but does not permit of the progeny continuing the race, at all events unless reinforced by the aid of one of the pure forms.

The several members of the group show mental differences quite as striking as those exhibited by their external form, and more than perhaps might be expected from the similarity of their brains. The patience of the ass, the high spirit of the horse, the obstinacy of the mule, have long been proverbial. It is very remarkable that, out of so many species, two only should have

or

There may be nineteen rib-bearing vertebrae, in which case five only will be reckoned as belonging to the lumbar series. The odontoid process of the axis is wide, flat, and hollowed above, as in the ruminants. The bodies of the cervical vertebrae are elongated, strongly keeled, and markedly opisthocoelous, or concave behind and convex in front. The neural laminae are broad, the spines almost obsolete, except in the seventh, and the transverse processes not largely developed. In the trunk vertebrae the opisthocoelous character of the centrum gradually diminishes. The spinous processes of the anterior thoracic region are high and compressed. To these is attached the powerful elastic ligament (ligamentum nuchar, paxwax") which, passing forwards in the middle line of the neck above the neural arches of the cervical vertebrae to which it is also connected-is attached to the occiput and supports the weight of the head. The transverse processes of the lumbar vertebrae are long, flattened, and project horizontally outwards or slightly forward from the arch. The metapophyses are moderately developed, and there are no anapophyses. The caudal vertebrae, except those quite at the base, are slender and cylindrical, without processes and without chevron bones beneath. The ribs are eighteen or nineteen in number on each side, flattened, and united to the sternum by short, stout, tolerably well ossified sternal ribs. The sternum consists of six pieces; the anterior or presternum is compressed and projects forwards like the prow of a boat. The segments which follow gradually widen, and the hinder part of the sternum is broad and flat.

As in all other ungulates, there are no clavicles. The scapula is long and slender, the supra-scapular border being rounded, and slowly and imperfectly ossified. The spine is very slightly developed; rather above the middle its edge is thickened and somewhat turned backwards, but it gradually subsides at the lower extremity without forming any acromial process. The coracoid is a prominent rounded nodule. The humerus is stout and rather short. The ulna is rudimentary, being represented by little more than the olecranon. The shaft gradually tapers below and is firmly welded to the radius. The latter bone is of nearly equal width throughout. The three bones of the first row of the carpus (scaphoid, lunar and cuneiform) are subequal in size. The second row consists of a broad and flat magnum, supporting the great third metacarpal, having to its radial side the trapezoid, and to its ulnar side the unciform, which are both small, and articulate inferiorally with the rudimentary second and fourth metacarpals. The pisiform is large and prominent, flattened and curved; it articulates partly with the cuneiform and partly with the lower end of the radius. The large metacarpal is called in veterinary anatomy cannon bone"; the small lateral metacarpals, which gradually taper towards their lower extremities, and lie in close contact with the large one, are called " splint bones.' The single digit consists of a moderate-sized proximal (os suffraginis, or large pastern), a short middle (os coronas, or small pastern), and a wide, semi-lunar, ungual phalanx (os pedis, or coffin bone). There is a pair of large nodular sesamoids behind the metacarpo-phalangeal articulation, and a single large transversely-extended sesamoid behind the joint between the second and third phalanx, called the "navicular bone."

The carpal joint, corresponding to the wrist of man, is commonly called the "knee of the horse, the joint between the metacarpal and the first phalanx the "fetlock," that between the first and second phalanges the " pastern," and that between the second and third phalanges the "coffin joint."

In the hinder limb the femur is marked, as in other perissodactyles, by the presence of a "third trochanter," a flattened process, curving forwards and arising from the outer side of the bone, about one-third of the distance from the upper çnd. The fibula is reduced to a mere rod-like rudiment of the upper end. The lower part is absent or completely fused with the tibia. The calcaneum has a long and compressed calcaneal process. The astragalus has a large flat articular surface in front for the navicular, and a small one for the cuboid. The navicular and the external cuneiform bones are broad and flat. The cuboid is small, and the internal and middle cuneiform bones are small and united together. The metapodals and phalanges resemble very closely those of the fore limb, but the principal metatarsal is more laterally compressed at its upper end than is the corresponding metacarpal. The joint between the femur and tibia, corresponding to the knee of man, is called the "stifle-joint "; that between the tibia and tarsus, corresponding to the ankle of man, the "hock." The bones and joints of the foot have the same names as in the fore limb. The horse is eminently "digitigrade," standing on the extremity of the single digit of each foot, which is kept habitually in a position approaching to vertical.

The muscles of the limbs are modified from those of the ordinary mammalian type in accordance with the reduced condition of the bones and the simple requirements of flexion and extension of the joints, no such actions as pronation and supination, or opposition of digits, being possible or needed. The muscles therefore which perform these functions in other quadrupeds are absent or rudimentàry. Below the carpal and tarsal joints, the fore and hind limbs correspond almost exactly in structure as well as function. On the anterior or extensor surface of the fimb a powerful tendon (7 in fig. 2). that of the anterior extensor of the phalanges (corresponding to the extensor communis digitorum of the arm and extensor longus digitorum

of the foot of man) passes down over the metacarpal bone and phalanges, to be inserted mainly into the upper edge of the anterior surface of the last phalanx or pedal bone. There is also a much smaller second extensor on the outer side of this in each limb, the lateral extensor of the phalanges. In the fore-leg the tendon of this muscle (which corresponds with the extensor minimi digiti of man) receives a slip from that of the principal extensor, and is inserted into the first phalanx. In the hind-leg (where it is the homologue apparently of the peroneus brevis of man) the tendon becomes blended with that of the large extensor.

A strong ligamentous band behind the metapodium, arising from near the upper extremity of its posterior surface, divides into two at its lower end, and each division, being first connected with one of the paired upper sesamoid bones, passes by the side of the first phalanx to join the extensor tendon of the phalanges. This is called in veterinary anatomy the " suspensory ligament of the sesamoids," or of the " fetlock" (10 in fig. 2); but its attachments and relations, as well as the occasional presence of muscular fibres in its substance, show that it is the homologue of the interosseous muscles of other mammals, modified in structure and function, to

suit the requirements of the horse's foot. Behind or superficial to this are placed the two strong tendons of the flexor muscles, the most superficial, or flexor perforatus (8) dividing to allow the other to pass through, and then inserted into the middle phalanx. The flexor perforans (9) is as usual inserted into the terminal phalange. Th the fore-leg these muscles correspond with those similarly named in man. In the hind-leg, the perforated tendon is a continuation of that of the plantaris, passing pulley-wise over the tuberosity of the calcaneum. The perforating tendon is derived from the muscle corresponding with the long flexor of man, and the smaller tendon of the oblique flexor (fbialis porticus of man) is united with it.

The hoof of the horse corresponds to the nail or claw of other mammals, but is so constructed as to form a complete and solid case to the expanded termination of the toe, giving a firm basis of support formed of a non-sensitive substance, which is continually renewed by the addition of material from within, as its surface wears away by friction. The terminal phalange of the toe is greatly enlarged and modified in form to support this hoof, and the size of the internal framework of the foot is increased by a pair of lateral fibro-cartilaginous masses attached on each side to the hinder edges of the bone, and by a fibro-cellular and fatty plantar cushion in the median part. These structures are all enclosed in the middle subcorneous integument, a continuation of the ordinary skin of the limb, but extremely vascular, and having its superficial extent greatly increased by being developed into papillae or laminae, From this the horny material which constitutes the hoof is exuded. A thickened ring encircling the upper part, called coronary cushion (13) and the sole (15), are covered with numerous thickly set