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Rrywar, M.A., LL.D. PROVBSSOR R; Ramsav WRIOHt, M.A, B.Sc. PRQngiKMt Gboro? M. Wroho, M.A. b*»emlSm>r: H. ft LamOTon, B. A, liJbrwiRft of th« University. M;g-t3»Bg>Wi!tt.lMM fthe mmty. ir 1 M U I . THE ANATOMY OF THE ORANG OUTANG By a. Primrose, M.B., CM., Edin. (Profeator of Anatomy in the Univertity of Toronto) mM, i TH THE ANATOMY OF THE ORANG OUTANG (SIM I A SATYRUS). [m AN ACCOUNT OF SOME OF ITS EXTERNAL CHARACTERISTICS: AND THE MYOLOGY OF THE EXTREMITIES. (Reprinted by permission from the Transactions of the Canadian Institute, tSgS-gg). A brief note concerning the external features of the Orang Outang was read by me before the Canadian Institute on December i8th, 1897. Since that time I have had an opportunity of dissecting the animal, and of consulting the literature on the subject. I propose, in this paper, to give a detailed account of some of its external features, and then to deal at some length with the anatomy of the muscles of the extremities. The musculature in the anthropoid apes is of great interest when studied from the comparative standpoint, and in the Orang, which I have been fortunate in securing, some unusual conditions present themselves which make the enquiry of special interest. The anatomy of the anthropoid apes has excited the interest of scientists for very many years. The old anatomist Tyson* described the Chimpanzee two centuries ago. Whilst his paper is entitled " The Orang Outang, or the Anatomy of a Pygmie," it would appear that the creature which he dissected was in reality a Chimpanzee. Many ana- tomists since the time of Tyson have been interested in the anatomy of the anthropoid apes, and the reason the subject possesses so much fascination for the scientific enquirer was well expressed by Owen' more than half a century ago, when he wrote : " In tracing the successive stages by which the lower animals approximate the structure of man, the interest increases as we advance, and becomes most exriting when we arrive at the highest term of the brute creation. At this point every deviation from the human structure indicates with precision its real I Edward Tyson, M.D., " Orang-Outang, sive Homo Sylvestrit, or the Anatomy of a Pygmie compared with that of a Monkey, an Ape. and a Man." London, 1699. 1 Richard Owen, "On the Osteology of the Chimpanzee and Orang Utan." Transactions of the Zoo- logical Society of London, Vol. L 1835, p. 343. .\U\ ! 4 PRIMROSE : THE ANATOMY OP THE ORANG OUTANG peculiarities, and we then possess the true means of appreciating those modifications by which a material organism is especially adapted to become the seat and instrument of a rational and responsible soul." Owen states that " the Orangs, or tailless apes of Africa and Asia, have long been recognized as the mammalia which make the closest approach to man ; and their organization has therefore been studied with more or less care and detail by many distinguished physiologists and comparative anatomists." This statement indicates the interest which had been manifested in the study of the anthropoid apes, more than half a century ago. In addition to the Orang Outang, the group of anthropoid apes includes the Gorilla and the Chimpanzee, which inhabit chiefly the west coast of Africa, and the Gibbon, which is found in the Indian Archi- pelago and some parts of the adjoining mainland. The Orang Outang is found in the islands of Borneo and Sumatra. It would appear that the creature never attains a great size. Huxiey remarks that there is no evidence that they exceed 4 feet 4 inches in height. On the other hand, Rudolf Fick states that Clark Abel is reported to have found a species of Orang in Sumatra which reached the height of two metres ; this, however, Fick considers a gross exag- geration. The specimen which I am about to describe was that of a young male animal (reproductions from photographs of the animal are published herewith). It measured 57 cm. in height. No history of its previous life and habits could be obtained. The shape of the cranium approaches, in many particulars, the human type. As has been pointed out by Hartmann' and others, the young apes approach more closely to the human type of skeleton than do the aged apes. Thus the great bony crests which are so characteristic of the skull of an aged male Gorilla are absent in young specimens. In all the smaller and middle-sized monkeys the general surface of the calvaria is oval and smooth, and remains so throughout life, whilst in the larger Baboons and Orangs there are well-marked supraorbital, sagittal, and occipital ridges.' These are said to attain thei"- greatest development in the aged male Gorilla, where, as Flower asserts, they completely mask the original form of the cranium. In my specimen (a young animal) the surface of the cranium was perfectly smooth, and in this respect resembled the skull of a man, as there were no indications of crests. It would appear, however, that the bony crests develop in connection I Robert Hartmann, "Anthropoid Apea." New York, 1886, p. 107. « W. H. Flower, " An Introduction to the Osteology of the Mammalin." London, 1885, p. 16a. n > i « ') connection ii photograph oj Ihe Oraiig Oiilaitg, taken after death. TTf. I'lom a l^hologniph of llie Oram; Oiitain;, taken after death. M I i 1 5; PRIMROSE : THE ANATOMY OF THE ORANG OUTANG with the skull fairly early. Thus Delisle' observes that many crania exhibit well-developed sagittal crests, whilst as yet osseous union has failed to occur between the basioccipital and the basisphenoid. In man this union occurs about the twentieth year. Delisle describes the skull of an Orang, which exhibited this and other 5igns of youth, in which the crests were apparently in an early stage of development ; the frontal crests, instead of uniting at the bregma'to form the sagittal crest, passed backwards close to the superior border of the parietal bones, on each side of the sagittal suture, quite independently of each other, being separated by an interval of 2 cm. until they reached the occipital crest. This interparietal ridge may rise, according to Owen,^ in the adult animal, to the height of one-third to two-thirds of an inch above the general surface. These crests give a mass ^e appearance to the skull, but as Owen' long ago showed in his description of the skull of a Gorilla, the skull may be actually lighter than it is in man. This unexpected result is due to the greater size and extent of the air cells. Owen found that these extended in the Gorilla backwards from the tympanum, along the base of the occipital crests, as far as their junction with the parietal crest, and forwards also to the sphenoidal sinuses ; the frontal sinuses, and the antrum, were also developed to an unusual extent. ».' '/ The dental formula in the Orang is similar to that of man. In my specimen none of the permanent teeth had as yet erupted, and the for- mula was as follows : — Mi'k teeth. 2-2 I - I 2-2 I C M = 2o a-2 I - I 2-2 One finds that the dental formula in all the anthropoid apes is the same as that of man, and, in fact, such is the case in all the old world apes, with the exception of the Lemurs ; whilst, on the other hand, among the American apes there is considerable variation. The lips are very wide and possess a wonderful degree of mobility. The mouth, in the living Orang, is said to be closed as a rule ; but, when the animal is taking food, the lips are used in a very curious I Ueliale, " Sur roat^lo^ie dn Orang-utans." Comptet Reiilus de I'Acadimie dei Sciences. Paris, 1894, Vol. CXIX, p. 141. > L(K, cit., p. 3j6. 3 R. Owen, " Oateologncnl Contributions to the Natural Historyof the Chimpanzees, etc." Transactions of the Zoological Society of London, Vol. Ill, 1848, p. 41a. ;l I M 6 PRIMROSE : THB ANATOMY OF THE ORANO OUTANG fashion. Thus, Fick' states that the lower lip may be protruded so as to form a kind of natural cup, so that if, for example, milk be given to the creature, he can fill this cup formed by the protruded lip, and then proceed to sip or lap the milk out of it Darwin' refers to the protru- sion of the lips in discussing the expression of the emotions in animals- He states that the lips of young Orangs and Chimpaniees may be pro- truded to an extraordinary degree ; they thus act, not only when angered, sulky, or disappointed, but when alarmed at anything and like- wise when pleased. T' 2 eyelids are wrinkled, so that a series of grooves, paraile' to the free margin, exists both in the upper and the lower lid. From the pal- pebral margin project well developed eyelashes. The eyes are never widely open in the Orang. They are placed very close together ; Fick found, in the adult Orang that the pupils were only separated 5.7 cm., whilst in the emmetropic human eye they were se^ ii'e.':ed 5.9 cm. One of the most characteristic forms of expression in man is produced by the wrinkling of the forehead. Apparently the Orang does not pos- sess this power to the slightest degree, although several observers have found the corrugator supercilii muscles present — muscles which produce the wrinkling of the forehead in man. It would appear, therefore, that the Orang has lost the power of using these muscles much in the same manner as man has lost the power of moving the ears. This lack of power of moving the auricle may be commonly noted in man, although the muscles in connection with it are developed. The facial muscles of expression in general in the ape are poorly developed in comparison with the same group in man. Bischoff is no doubt correct when he states that man differs from all animals, and from the highest apes very essentially, in the strong development and isolation of the facial muscles of expres- sion. He concedes that the apes are excellent face-makers, but their emotions are expressed by distorting the whole face. The nose of the Orang is extremely short and depressed. There is no bridge and no point. The anterior nares look upwards and forwards. The shape of the ear in the Orang is remarkably like that in man. It possessed, in my specimen, the Darwinian pointed tip. This ^xjint, to which Darwin directed attention, consists of a small blunt process which projects inwards from the in-folded margin (the helix). In many monkeys the upper portion of the ear is slightly pointed, and the margin is not I Rudolf Fick, " Vergleichund anxtomiKhe Studien an einen erwachaenen Oranr-Utang," Archiv fUr Anat. und Phya. Anat Abth., 1895, p. 1. M Charles Darwin, " Th« Expreuion of the Emotion* in Man and Animals." London, 1871, p. 140 3 Charles Darwin, "The Descent of Man." London, 1871, Vol, I, p. Ji. PRIMROSE : THE ANATOMY OF THE ORANG OUTANG Diidon, 1873, p. 140 at all folded inwards. This condition, according to Darwin, occurs in monkeys which do not stand high in the order, as Baboons and some species of Macacus. When, however, the whole ear is pressed perman- ently backwards, and the margin is infolded, as in the higher apes, the point persists as the process mentioned. Darwin's point is found very frequently in the human ear, and whilst it is often absent in man, it is also not infrequently absent in the anthropoid apes. In my specimen, the lobule of the ear was entirely absent. This peculiarity, too, is often found in man. The ears projected in a fairly well-marked fashion from the side of the head, although not more so ♦^han is the case in many human ears. There was no prominence in the region of the chin in my Orang, and in this particular, it agrees with other anthropoid apes ; in fact, the for- ward projecting chin may be looked upon as a fairly distinctive human characteristic ; although Huxley states that in certain of the Gibbons (the Siamang) he found something approaching to a chin. He says, however, that this " is the only ape which has anything like a mental prominence." Again, Huxley remarks that whilst the chin in the European is either straight or projects beyond the level of the incisor teeth, in the lower races it retreats somewhat, although this recession appears greater than it really is, because of the prominence of the teeth.* In my Orang the recession of the lower jaw was such that a continuous curve was formed, which extended, without interruption, from the margin of the lower lip above to merge below in the outline of the neck. The short thick neck of my Orang is a characteristic common to all anthropoids. The short^'ess of the neck is developed to a remarkable :A.,nt — to an extent seldom approached in man. It is due, not to shortness of the cervical spine, but, as Langer' has pointed out, to the shortness of the fibres of the levator scapulae, and of the descending part of the trapezius muscles. The result is that the shoulders of the Orang are raised considerably above the level of the sternum, and the head seems to be sunken literally between the shoulders. This brings about an oblique position of the scapulae, and a peculiarity of shape of these bones as compared with man. The Medical Timet and Gazette. t Huxley, "The Structure and Classification of the Mammalia." Vol. I and Vol. II. 1864. p. 6i8. s Ibid, Vol. I, p. 309. 3 C. Lander, " Die Musculatur der Extremitttten des Orang: als Grundlare 'liner vergleichend- myologischcn Untersuchung." Sitz. der math-natur. Clasae der kais. Acad, der Wisscnschalten, Vol. LXIX. Wien, 1879, p. 178^. Jji m ■ l!'.' ml m % !"» m PRIMROSE : THE ANATMOV OF THE ORANG OUTANG In the cheek of man there exists what is called the buccal fat pad. This is a circumscribed mass of lobulated fat lying upon the buccinator muscle and the anterior margin of the masseter muscle, closely sur- rounding the duct of the parotid gland. It is particularly well devel- oped in the cheek of the infant, and has been called the "sucking pad " on account of its supposed function in connection with the act of sucking. Symington' has demonstrated the relations of this pad of fat in the cheek of the child, and has figured the pads as they appear in coronal section through the cheek. Ranke'' states that the existence of this pad was first described by Heister in 1732, who, however, mistook it for a gland, and called it the "glandula molaris ;" and later anatomists followed this erroneous view. Ranke showed that it was surrounded by a connective tissue envelope, through which it was connected to the underlying buccinator muscle, and that a deep process of the mass passed backwards and upwards into the spheno-maxillary fossa under the ramus of the jaw and the lower part of the temporal muscle. It was found well developed in a four months' old foetus, and, while it persists throughout life, it is more notice- able as a well-defined structure in the infant. A peculiarity of this cheek pad is that, according to Ranke, it withstands the destructive processes which destroy tli^ subcutaneous fat in many wasting diseases. Macalister* is apparently in error in making a statement to the con- trary. These pads become unduly prominent when the neighbouring subcutaneous fat of the cheek wastes away. This sucking pad in my Orang was remarkably well developed. It formed an isolated mass completely separated from the subcutaneous fat, and presented all the features described as characteristic of it in the human infant. In the Orang, as age advances, enormous masses of fat develop in the cheeks and in the neck. It is not certain whether or not these cheek pads are developed from the sucking pad already described — probably they are rather developed from the subcutaneous fat. At all events, in the old Orang, thc^e later developments of fat attain great dimensions. They are fully described and figured by Fick.* According to his state- ment, they had not been previously described, but we find that Huxley " mentions them as occurring in an adult male Orang. The extreme I Johnson Symington, " The Topographical Anatomy ot the Child." Edinburgh, 1887, p. 14. a H. Ranke, ** Ein Saugpolater iti der menschlichen Backe." Virchow's Archiv fUr path. Anat. und Phy»., Vol. XCVII, i88:, p. 517. 3 A. Macalinter, " A Text book of Human Anatomy." London, 1889, p, 366. 4 Loc. cit., p. a. 5 Loc. cit.. Vol. I, p. 564. PRIMROSE : THE ANATOMY OF THE ORANG OUTANO m ugliness of the old Orang is largely due to the existence of these cheek and ne^k pads. They form on each cheek semi-lunar appendages covered by the skin. In the dead Orang, Fick described them as tri- angular in shape. The free apex of the triangle was at the level of the malar bone, whilst the attached base of the triangle extended from the top of the frontal bone downwards to the lower margin of the lower jaw and face. Fick suggests that it occurs only in old age and in the male sex. These masses of fat are, to some degree, mobile; and Fick figures an Orang lying asleep, in which the cheek pad having fallen forwards, forms a cushion for the creature to rest its head upon. A similar development of fat occurs in the neck of the old Orang. Deniker and Boulart' describe similar voluminous pads of fat in the Orang — one 6 cm. thick, extended under the occiput and the nape of the neck ; two others, in the form of semilunar crests i8 cm. long and ii cm. wide existed on the side of the face and upon the jaws, and gave the animal a most singular appearance. This development of fat in the Orang appears to be connected with the age of the animal, and Fick suggests that it is comparable to the accumulation of fat which is apt to occur in man after a certain age is reached. In my Orang there were no such free appendages of fat, but a mass of fat existed be.ieath the jaw, extending down over the hyoid bone and the larynx. Embedded in this were two thin walled sacs which were found to communicate with the air passages. They were in fact diverticula from the larynx, and were pyriform or egg shaped, attached above in the neighbourhood of the thyro-hyoid membrane; they diverged from one another, passing out under the sterno-hyoid muscles and after appearing in the neck on either side at the posterior border of this muscle, they came forwards towards the middle line. The sac upon the left side measured 5 cm. in its long axis and 2.3 cm. in its greatest width. The right sac measured 2.5 cm. long and 1.5 cm. wide. The sacs were very readily separated from the mass of fat in which they were embedded. It would appear that these sacs occupied an unusual position in my Orang in their relations to the muscles. In the descriptions which I have been able to consult they are figured as appearing in the middle line of the neck between the infra-hyoid muscles, whilst in my Orang they passed out behind these muscles and appeared at the posterior border of the muscles in the manner described. It is in the median position that Vrolik' des- cribes and figures them in the Chimpanzee, as do also Deniker and I J. Deniker and i .. Boulart, '* Sur divers points de I'Anatomie de TOrangr-Outan." Comptes Rendus de I'Academic des Sciences. Vol. CXKX, 1894, p. 336. ft ':> II !!■* hI h. 1 1 Iff I If a W. Vrolik, plate a. ' Recherches d'Anatomiu compar^e sur le Chtmpans^," Amsterdam, 1841. p. 44 and I' -' 10 PRIMROSR : THE ANATOMY OF THE ORANG OUTANO Boulart' in the Orang. In former descriptions it has been assumed that these sacs are found only in the older animals ; the great development of them in my young specimen disproves this statement. It would seem that they are seldom developed symmetrically, but one sac is always larger than the other. This disparity in siiie may be great: thus Deniker and Boulart found in one Orang the left sac measured ii cm. long, whilst the right sac in the same animal was only 41 mm. The larger sac also often overlaps the smaller, and may completely conceal it lying in the middle line of the neck ; this probably accounts for the circum- stance that some anatomists have been led to describe the sac as a single azygos structure. Careful search in cases where the sac appeared single has led to the discovery that both sacs were present, one being of very diminutive proportions. Huxley^ describes the great development of these sacs in a Gorilla in the following terms : — " The larynx in its general characters resembles that of man and the Chimpan- zee ; connected with it in the adult Gorilla is a system of great cavities, developments of the two laryngeal sacculi, each of which is equally dilated, and produced into large caecal sacculated pouches, extending all over the sides of the neck in the interspaces between the muscles, from the rami of the lower jaw to the axillae. As age advances the sacs of the tA'o sides coalesce in the middle line over the trachea, and form an elongated bag, the upper end of which fits into the hollow of the body of the hyoid bone. The use of this immense and complex apparatus " Prof. Huxley adds " is not known." The most extensive development of the laryngeal pouches is found in Duvernoy's description of the Gorilla.' In an adult male Gorilla a large median portion situated in the middle line of the neck was found, from which three pairs of lateral prolongations passed. Two superior ones, one on either side, passed upwards behind the angle of the lower jaw, passing back beneath the sterno-hyoid, the umo-hyoid and the sterno- mastoid muscles ; these superior branches of the median sac had the most direct communication with the ventricles of the larynx into which they opened, immediately between the hyoid bone and the thyroid cartil- age. These two superior branches also communicated each by a large aperture with the great median sac which descended anteriorly over the thorax and gave off a second and a third pair of lateral branches, with each of which its cavity freely communicated. The second pair (median) ■ Deniker and Boulart, " Les Saca Lnryngrieni des Singea anthropoides," Journal de I'Anatomie et de la Phyaiulogie, Paris, 1886, p. 51. a Loc. ciu. Vol. I, p. 538. 3 M. Duvernoy, " Des caractires anatomiques des grands singes pseudoanthropomorphes," Archires du Museum d'Histoire Naturelle, Paris, i8j5-g6, pp. aoi, joa. aoj. PRIMROSE : THE ANATOMY OF THB ORANG OUTANG 11 « rAnatomie et de >rphes," Archives descended to meet the clavicle, lyine over its upper border as it passed outwards beneath the sterno-mastoid muscle to the upper part of the shoulder. The third (inferior) pair were by far the largest. They ap- peared to be derived as a bifurcation of the great median sac at its lower extremity. They extended downwards among the muscles of the anterior wall of the chest, each branch passing out laterally under the clavicular portion of the deltoid and downwards under the tendon of the great pectoral muscle and, whilst under this, insinuating itself between the two portions of the small pectoral muscle (superior and inferior) into which that muscle divided in the animal, passing even to the axilla, and lying there upon the lateral wall of the chest. Huxley' in his description of the Orang states that the laryngeal saccules attain still more enormous dimensions in the adult than in the Gorilla; he describes them as constituting a great median bag covered by a strong layer of muscular fibres from the platysma and sending caecal prolongations backwards beneath the trapezius muscle as far as the occiput, beneath the scapula and into the axilla. The cavity com- municated by two distinct canals with the ventricles of the larynx. Huxley tells us that among the Gibbons there is only one species — the Siamang — in which a laryngeal pouch at all similar to that found in the other anthropoids exists. One finds a description of laryngeal sacs in the Chimpanzee by Gratiolet and Alix'' in which the left pouch extended down between the sterno-mastoid muscles a centimetre beyond the upper margin of the sternum. Cunningham determined the relations of the laryngeal sac in a Chimpanzee and in an Orang by means of frozen sections. In the Chimpanzee it extended downwards in front of the sternum to the lower border of the manubrium ; it stretched in an upward direction until it reached the hollow posterior surface of the hyoid bone. In the Orang the laryngeal pouch, although it was pro- longed down to the top of the sternum, was not continued on to the anterior aspect of that bone. The occurrence of these sacs in the lower apes has been mentioned by Huxley, who found that among monkeys and baboons of the old world the sacs exist in many species ; they are not a development of the laryngeal ventricle in these animals, however, but grow out from the thyro-hyoid membrane, and have only a single aperture of communi- I Loc. cit., Vol. I, p. sq6. a Gratiolet and Alix, " Recherches aur I'Anatomie du TroKlodytes Aubryi," Nouvellcs archives du Museum J'Hiitoire Naturelle, Paris, Vol. II, 1866, p. S3S. , 3 D. J, Cunningham, "The Topo,^>2phical Anatomy of the Chimpanzee, Orang^-utan and Gibbon," Cunningham Memoirs, Royal Irish Academy, 1886, p. 138, '■ i' i It ■: I III ••11 Pi %i' ■-l;l ^•llii PI ;'-';'l !':;4i| !^''iii ill Mill .il'iil ■Hi! ill 13 PRIMROSE : THE ANATOMY OP THE ORANQ OUTANQ cation with tlie laryngeal cavity. In the apes of the new world some extraordinary variations occur in the development of these air sacs. In the spider monkey (Ateles) Huxley describes a single median sac which is developed at the back of the trachea, opening into the air passages between the upper ring and the cricoid cartilage. Then, again, in the howling monkey (Mycetes), according to the same authority, the hyoid and the laryngeal apparatus is exceedingly developed and modified. " The body of the hyoid bone is expanded into a great rounded drum with thin osseous walls, the larger cornua projecting backwards from it, though the lesser pair are quite obsolete. The thyroid cartilage is also exceedingly large, and the epiglottis undergoes an extraordinary development and changes in form. The cavity of the glottis presents several prolongations ; one long and narrow tube in front communicates with the chamber in the body of the hyoid bone, the two lateral sacculi are prolonged upwards on each side, and are only separated from each other above the larynx by a thin membranous septum, and in some species there is, in addition, a small inferior pair of sacs." • The howling monkey, as its name implies, is capable of uttering loud and discordant sounds, and no doubt the complicated apparatus just described has something to do with the production of these sounds. It is difficult to understand how the mechanism acts, and I am not aware that anyone has succeeded in solving the problem. I have thus given an account of the laryngeal sacs as they are found in the anthropoid apes and in apes lower in the scale. They are undoubtedly developed in connection with the laryngeal ventricles^ structures which are present in the human larynx. These ventricles — the " ventricles of Morgagni " — lie in the lateral walls of the larynx, one on each side. The ventricle may be described as a recess which exists between the false cords above and the true cords below; it there forms a diverticulum from the lateral wall of the larynx, presenting an elliptical opening, the length of which is a little shorter than the true cords. The ventricle is about 5 mm. in depth, and, in man, from the anterior part a secondary diverticulum proceeds, the so-called " laryngeal pouch" which extends upwards for about 12 mm. towards the upper border of the thyroid cartilage ; it is apparently this laryngeal pouch which assumes such enormous proportions -n the Orang. According to Testut' this pouch is sometimes found considerably enlarged in man ; whilst it usually terminates at the upper border of the thyroid cartilage, it may proceed upwards as high as the hyoid bone, or even sufficiently high to • appear under the mucous membrane of the base of the tongue. I Loc, cit. Vol. II, p. 113. 1 L. Teatut " Traiti d' Anatomic humaine," Troiiiime Edition, Paris, 189J, Vol. Ill, p, <59. PRIMROSE : THE ANATOMY OP THE ORANQ OUTANG 13 The function served by the laryngeal sac, as I have said, is a problem not yet solved. Fick observed a slight bellowing of the sac in the Orang when the animal was howling, and he also noticed a slight blowing up of the sac in the second or expiratory act of yawning. In coughing, on the other hand, no effect was noticed upon the sac. Sandifort long ago suggested that the sac permitted the storing up of air which was brought into use in prolonging the loud roar of the animal, but, as Huxley pointed out, the position of the sac above and not below the vocal cords is inconsistent with this theory. The great length of the arms in the Orang is a striking feature in comparing the animal with man. The lower extremities in man exceed the upper in length ; the reverse is true of the Orang. The measurements in my orang were as follows : Upper extremity 46 cm. Lower extremity .... 24 cm. The measurements were taken in the case of the upper extremity from the tip of the shoulder to the end of the middle finger, and in the lower extremity from the perineum to the heel, thus following, for the sake of comparison, the method adopted by Fick. We find, therefore, that the upper extremity measured 80.7 per cent, of the total length of the body, whilst the lower extremity measured 42.1 per cent, of the height. The following table will give the percentages in a comprehen- sive manner, the figures indicating percentages of the total length of the body from the head to the heel : Upper Lower Extremity. Extremity, The present specimen of the Orang 80.7% 42- 1% rOrang"Jumbo" 75-3% 38-3% '^""'nOrangr "Anton- 73-6% 37-9% Man 45 % 47-,S% Fick's measurements were taken from adult animals, whilst my Orang was quite young. The remarkable elongation of the upper extremities in proportion to the body length is not characteristic of the Orang only, but of all the anthropoid apes. In the Gibbon this feature is even more marked than in the Orang or than in all other apes. It is interesting to note in this connection that the arms of negroes are proportionatc;ly longer than in the white races, this being, however, chiefly due to the increased length of the hand and forearm. Huxley tells us that the native Australians and other low races resemble the negro in this respect. One must note also that in this peculiarity anthropoid apes differ in a marked degree from 'i ''■•til' ■'^ V If', 'Jil I'; 'I 14 PRIMROSE ! THR ANATOMY OF THB ORANO OUTANO the lower apes. Thus, in the lower apes, with very few exceptions, one finds that the lower extremities exceed in length the upper. In the Lemurs the hind limbs exceed the fore limbs to a very marked degree. The hind limbs of the Orang are always bent ; it is impossible to straighten them completely. This is mainly due to the arrangement of the muscles at the hip and the knee. On the other hand, the fore limbs may be straightened out perfectly. I leave for consideration in another part of this paper the question as to whether the Orang is four handed or not, but in the meantime I shall speak of the " hand " of the fore-limb, and the " foot " of the hind limb. The hand of the Orang is very much longer and narrower than the human hand. Thi** is largely due to the great elongation of the metacarpal bones, but, in iition, the phalanges too are proportionately longer than they are in m. Fick states that the Orang grasps things by preference with the right hand, and that in all other manipulations they are decidedly right handed, as is common in most apes. The thumb is very short and rudimentary; it does not project as far as the head of the metacarpal bone of the index finger, and the ball of the thumb can hardly be said to exist. Much more remarkable, however, is the foot of the Orang. Like the hand, it is very long and narrow, but it has a well developed opposable hallux and is evidently modified as a grasping organ. The four outer toes are greatly elongated and remain separate, so that they resemble the fingers of a hand rather than the toes of a foot. It would appear that the Orang never stands erect without some support from the arms. Thus it may stand upright whilst it supports itself by grasping the limb of a tree overhead, or it may rest the fore limbs on the ground. Mayer' and others have observed that whilst resting on the fore limbs the Orang, like other quadrumana, does not place the palm of the hand on the ground when walking, but rests upon the outer margin and the back of the wrist and fingers. Whilst standing the foot is supinated and the toes bent, the foot resting upon its outer margin. This differs from the Gorilla, which is able to stand erect without the support of the arms, and is capable also of bringing the sole of the foot to the ground. The lines upon the integument of the palm of the hand and of the sole of the foot in the Orang may be compared with the markings which exist upon the integument of the human sole and palm. If the palm of the hand in man be examined (see photograph) one may readily observe that the markings upon the palmar aspect of the finders themselves are ■ Mayer. . . " Zur Anatomic dea Orang-Utang und des ChimpanM.' Berlin, 1856, p. 185, ArchivlfUr Naturreichichtc, '"l>! eptions, one )er. In the ted degree. [ipossible to ingement of le fore limbs ideration in rang is four "hand" of if the Orang his is largely iition, the an. Fick : right hand, »t handed, as limentary; it : of the index exist. Much the hand, it is le hallux and luter toes are )le the fingers lat the Orang Thus it may imb of a tree Mayer' and 3S the Orang, hand on the d the back of nated and the iffers from the ■ the arms, and nd. and of the sole larkings which If the palm of readily observe themselves are v|fUr NaturiteKhichte. ":i From a fi/io/ograph of Ihc palm of the hand of an adult man, shoiving the markings on the palm of the human hand. * * From a pholct^iaph of i/tc palm of l/iv liaiiil of llu' Oraiv^ Oiilnns;, s/unviiig the markings on tilt inligiiiiienl of tin pii/iii. he markings ' ., , ■ 1^; : '■ \ t m :i ■i -4 ll PRIMROSE : THE ANATOMY OF THE ORANG OUTANG IS obviously associated with the flexion or bending of the digits, the grooves existing opposite the joints at which the movement in question takes place. These grooves are converted into deep clefts when the fingers are fully bent. In the palm proper, similar markings on the skin are observed. Two very noticeable ones run almost parallel to one another from near the base of the index finger inwards towards the inner border of the palm. These grooves are about i cm. distant from each other- They do not run transversely across the palm, but their course is very oblique, the inner extremity of eacl line being much nearer the wrist than the outer extremity. These markings are associated with the flexion of the fingers upon the palm, and are converted into deep fissures when the fingers are folded in upon the palm. Certain markings run in a more longitudinal direction. These begin near the wrist. One is clearly associated with the movements of the thumb towards the palm ; it curves forwards from the mid-point of the wrist, around the base of the ball of the thumb, to terminate on the outer border of the palm, some- times joining the nearer of the two oblique lines already described. This curved line is converted into a cleft when the thumb is opposed to the palm or to the other digits ; it is therefore clearly associated with the movement of opposition of the thumb to the palm or the other digits. Other longitudinal markings are associated with the adduction or abduction of the fingers. Occasionally the ball of the little finger is also marked off by a more or less distinct curved line. Now, if we compare the foregoing with the markings which are observ- able in the photograph of the palm of the hand of our Orang (see reproduc- tion of photograph) we find a corresponding series of markings. We notice, however, that the ball of the very rudimentary thumb in the Orang is not developed to anything like the proportions attained ',i man. The curved line at the base of the thenar eminence is present, but what is more marked is the cleft which indicates adduction of the thumb rather than opposition. Then one observes a very marked difference in the markings running acro.ss the palm. These are remarkable in being transverse rather than oblique in direction. We observe also certain less clearly marked longitudinal lines associated with adduction and abduction of the finger Let us now consider the significance of the difference in the markin^.i in the human hand compared with those of the Orang. Professor Goodsir, of Edinburgh, long ago' well indicated a distinctive difference between the hand of man and that of the ape when he stated that the hand of man could grasp a sphere whilst the hand of the ape could grasp a cylinder. I " Guodair's Anntomical Memuirt," Edited by Prof. Wm. Turner, Edinburgh, 1868, Vol. I, p. 239. il '\ iiSi '■■ ■' llil !t-;:"i ^■:::';i i6 PRIMROSE : THE ANATOMY OF THE ORANG OUTANG Clearly the oblique grooves in man indicate that the fingers are not bent in a perfectly straight direction into the palm, but are directed somewhat obliquely towards the thumb, hence the line associated with that movement of flexion is oblique, in other words it is at right angles to the line of movement — the fingers are opposed to the thumb. In the Orang, on the other hand, the fingers are flexed directly into the palm, and the animal is thus better able to grasp a cylindrical object, such as the bran'-h of a tree, whilst it is not so well adapted to grasp a sphere, as the har d of man. The development of the ball of the thumb in man is due to the presence of a well-developed group of muscles which have to do with adduction and opposition of the thumb. These muscles are by no means so well developed in the hand of the Orang. It must be noted, however, that the groove of opposition is present in the Orang, and that the feeble thumb can be opposed. In the Orang, too, there is a marking off of the ball of the little finger ; this is sometimes, but not always, present in the hand of man. One would readily suppose that the lines in the palm of the hand were produced after birth when the muscles of the hand had brought about the various movements, but such is not the case. Professor Sir William Turner' makes an interesting observation regarding this when he says : "These grooves are present in the infant's hands at the time of birth; and I have seen them in an embryo, the spine and head of which were not more than 90 mm. (three and a-half inches) long. They appear in the palm months before the infant can put its hand to any use ; though it is pos- sible that the muscles of the thumb and fingers do, even in the embryo, exercise some degree of action, especially in the direction of flexion. These grooves are not, therefore, acquired after birth. It is a question how far the intra-uterine purposeless movements of the digits are suffi- cient to produce them ; but even, should this be the case, it is clear that they are to be regarded as hereditary characters transmitted from one generation of human beings to another. They are correlated with the movements of the digits, which give the functional power and range of movement to the hand of man." It may be remarked here that the grooves on the palm differ some- what in the different anthropoid apes ; thus Hepburn' shows that the lines across the palm in the Gorilla are decidedly oblique, and the hand ■ W. Turner, "Some Diitiactive Characters of Human Structure," Report of the British Association for the AdvHncement of Science, iSqfj, p. 768, a David Hepburn, "The IntetrumenUry Grooves on the Palm o( the Hand and the Sole of the Fool of Man and tlie Anthropoid Apes," Journ. of Anat, and Phys., Vol, XXVIl, iS9a-',^3, p. 111. PRIMROSE : THE ANATOMY OF THE ORANG OUTANG «7 n Britiih Asaociation of the Gorilla in this respect more closely resembles the hand of man than does the hand of the Orang. The great length and narrowness of the hand has been referred to ; it is quite obvious, however, that the fingers of the Orang are disproportion- ately short as compared with the greatly elongated palm. The cause of this is demonstrated by Langer' in his dissection of an interdigital membrane which spreads out over the upper fourth of the proximal phalanx of the four inner digits. This membrane is not present in man, and in the Orang, therefore, more of the proximal phalanx is sunken into the palm than is the case in man. The result is that the fingers of the Orang appear proportionately short. Another effect will be observed by reference to the photographs here reproduced, namely, that the integ- umentary grooves are further separated from the interdigital clefts in the Orang than they are in man. Dr. Blake,'' in his observations on the study of the hand for indica- tions of disease, has noted the remarks made by Dr. Harry Campbell regarding the curious resemblance between the acq li red bone and skin changes in the acromegalous subject, and the condition normal in the hand of the Gorilla. It would appear that many of the mor- bid changes in this disease bring about conditions of the character referred to, and Blake would view such as examples apparently of reversion to a primitive arboreal type. Whilst I am not prepared to seriously entertain this idea, there is no doubt of the fact, at all events, that in this disease the hand of man comes to present a curiously close resemblance, in appearance, to the hand of the Gorilla. Turning now our attention to the markings in the sole of the foot, we find that in the human foot these are largely obliterated after the individual has walked about, and pressure has been brought to bear upon the sole, the skin becoming as a result thick and indurated. Some interesting observations on these integumentary markings, as they appear in the foot of the infant, have been made by Dr. Louis Robinson' in the " Nineteenth Century." He looks upon the markings on the infant's foot as giving some evidence of the evolution of the human foot from a structure which at one time was able to grasp an object after the manner of the human hand or the foot of an anthropoid ape. Robinson states that these lines are scarcely visible at fourteen months and are only present in a few cases after two years of age, 1 Loc. cit,, pp. i8a and i8j. 2 Edward Blake, M.D.. "On the Study of the Hand for Indications of Local and General Diseaw," London, 1889, p. :f&, 3 Louis Robinson, M.D., " The Meaning of a Baby's Footprint." The Nineteflnth Century, Vol. XXXI, 189a, p, 795, ': .': ' ' 11 I' " i'i i8 PRIMROSE : THE ANATOMY OF THE ORANC OUTANG whilst in the adult they disappear. I have, however, photographed the sole of a child's foot aged nine years (see reproduction of photograph), and find well marked all the lines described and figured by Robinson in the foot of the infant, I shall proceed to describe these lines and to enquire into their significance. In the child of nine years one is able to distinguish the lines which correspond to the oblique lines across the palm. In comparing the foot with the hand, however, one must bear in mind that the great toe (unlike the thumb) is parallel in position to the other digits, and that its metatarsal bone is closely united to the other digits by an extension of the transverse metatarsal ligament, whilst in the hand there is no such connection of the metacarpal bone of the thumb to the index finger. The hallux is therefore not free to move about in the manner characteristic of the thumb. Moreover the hai.Jx cannot be Oj-posed to the sole or to the other digits, and if we examine the muscula- ture in man we find there is no opponens hallucis. On examining the markings in the sole of the foot of the child (see photograph) we find a line strongly curved starting at the inner border of the foot at the base of the first digit, and passing outwards and forwards to terminate immedi- ately external to the cleft between the first and second digits, its point of termination separated i . 5 cm. from that cleft This line marks off what is commonly called the ball of the great toe, but observe that the so-called ball of the great toe does not correspond with the ball of the thumb, in that the soft structures forming the ball of the great toe are related to the plantar aspect of the proximal phalanx of that digit ; whilst the ball of the thumb is formed by structures related to the palmar aspect of its metacarpal bone. This curved marking in the sole is therefore opposite the metatarso-phalangeal joint, and corresponds to the marking on the palmar aspect of the thumb opposite the metacarpo- phalangeal joint of that digit, and not to the curved marking at the base of the thenar eminence. This curved line in the sole therefore is produced by flexion of the hallux at the metatarso-phalangeal joint. If we look for any marking in the sole produced by opposition or adduction of the great toe in man we look in vain. There is no such marking, and therefore the characteristic mark found in the palm bounding the thenar eminence is wanting in the sole. We find, how- ever, a curved line across the sole beginning at the base of the second digit and running at first somewhat longitudinally for a short distance and then curving outwards to end at the outer border of the foot. This curved line is often interrupted in the sole, but can always be readily distinguished. It is frequently spoken of as limiting the ball of the little toe, but it too is opposite the metatarso-phalangeal joint and is therefore merely an indication of the flexion of the smaller toes at that led the sole )h), and find 1 the foot of inquire into distinguish ; palm. In n mind that o the other other digits in the hand lumb to the bout in the : cannot be he muscula- amining the )h) we find a It the base of late immedi- r\ts, its point ne marks off erve that the le ball of the great toe are f that digit; ;lated to the ig in the sole orresponds to le metacarpo- irking at the e therefore is langeal joint, opposition or ;re is no such in the palm We find, how- of the second short distance he foot. This ys be readily he ball of the al joint and is ler toes at that ■I 1 .1, 1' Ml I 'I ;.^l i'" ^ f -!;■'! M . From a photograph of the sole of the foot of a i^irl nine years of age, showing the mariings on the sole of the human foot. ''II'..!' i From a photograph of the sole of the foot of the Oraiig Oittavg, showing the markings on the iute!;iimeut of the sole. \ ■\ 1 1 «' * f '' ll ' ' # .1l f l'^ ' 1 s > Mml to to sc tc g' m rri w ir ai rs a it a II t} tr al (^ b tl li w r( tl 1 o o a P b li tl a ii V P PRIMROSE : THB ANATOMY OF THE ORANG OUTANO >9 point. It frequently joins the curve described at the base of the great toe. The great obliquity of this groove in the human foot is due not to the fact that the toes flex towards the great toe (compare the de- scription of the hand) but to the fact that the metatarsal bones of the toes become progressively shorter as we proceed to the fifth digit, the groove in question lying over the heads of the metatarsal bones. Let us now compare the foot of the Orang with that of man. The markings in the sole of the foot in the Orang are more distinct than in man because the animal does not obliterate them in walking, during . which the outer margin of the foot alone comes to the ground; the outer margin is in consequence smoother than the remaining portion of the sole. We are at once struck by the great length of the four outer toes, they are long, and are separated from one another so as to resemble fingers rather than toes. The great toe in the Orang's foot, however, presents a remarkable difference from the hallux in man. Thus in the Orang it is very much shorter than the other toes, and its long axis forms a marked angle with the long axis of the remaining part of the foot. It is capable in fact of being placed at right angles to the long axis of the sole. The metatarsal bone of the great toe is not connected by a transverse metatarsal ligament to the second digit, and in this respect also differs from the human foot. The ball of the great toe in the Orang (as observed in the photograph) is marked off by a well marked groove, but this groove is not opposite the metatarso-phalangeal joint but opposite the tarso-metatarsal joint and marks off the mass of muscular tissue which lies in relation to the plantar aspect of the metatarsal bone. In other words the line is associated with adduction and opposition, and in this respect entirely corresponds to the line described in connection with that movement in the human hand or in the hand of the Orang itself. The lines running across the sole at the bases of the other digits are oblique and very similar in their position and characteristics to those observed in the palm of the hand. The obliquity here may partly be accounted for by the gradual diminution in length of the digits as we proceed from the second to the fifth digits, but is also accounted for by the fact that the Orang flexes its toes not directly into the sole, but somewhat towards the hallux, the mark being at right angles to the line of movement in flexion. The lines corresponding to the flexion of the digits themselves are well marked opposite the metatarso-phalangeal and the interphalangeal joints. Note that in the Orang the line indicating flexion of the hallux at the metatarso-phalangeal joint is well marked, but is separated from the sole proper and lies upon the plantar aspect of the hallux itself, differing thus in its position and , ,: ;'iH M PRIMROSE : THE ANATOMY OP THE ORANO OUTANG relation to the sole as compared with the condition on the human foot but nevertheless corresponding to the curved line at the base of the so-called ball of the great toe in man. A few longitudinal grooves are observable on the sole of the Orang ; these are due to adduction of the digits towards one another. It will thus be observed that in studying the foot of the Orang it bears more resemblance to a hand than a foot. In fact as an instrument for grasping objects it is much more serviceable than the hand of the same animal. The hallux is more strongly developed than the pollex, and the movements of opposition and adduction are much more strongly carried out by the foot than by the hand. The Orang could grasp a sphere with the foot much more readily than with the hand. If, therefore, we were to restrict our considerations to the markings in the integument, as indicating the use to which the member is put, we might be led to conclude that the posterior extremity of the ape ended in a hand and not in a foot. On t " other hand, as ue shal . observe later when we proceed to describe the 'ssection of the crep.cure we shall be forced to admit that morphological;; ' - structure in question is a foot and in no sense a hand. We shall ta.. -m opportunity of referring again to this subject after the anatomy c." "ihe soft parts has been described. Concerning the manner in which the Orang uses its hands and feet in progression one may quote Hwxley's remarks. He says : " it very unwillingly assumes the erect fiOKt-ire, perhaps never in its native haunts. When it walks upon the gr .>und it swings itself along by its very long arms as with crutchc,-., i ot resting exactly on the knuckles, as the great African apes, but with the inner edge of the index finger on the ground and the thumb spread out. The hind foot does not come flat to the ground, but rests upon its outer edge with the toes close together and curved. Even when passing from bough to bough of the trees among which its life is chiefly spent, it observes a remark- able slowness and caution in its movements.'" The Myology of the Extremities. The Trapezius arose from all the dorsal spines, from the Hgamentum nuchae and, by an origin 2 cm. wide from the occipital bone. It was inserted into the outer third of the clavicle, the acromion process and I Loc. cit. Vol. I. p. 564. a My colleague, R. D. Rudolf. M.D,, Edin,, diuected the rightildeof the Oran^, and noted in detail the connections and relation* of the musclri of the fore and the hind limbs. I have noted throughout my paper those points in which Dr. Rudolfs account differed from the results obtained by me in the dissection of the left side of the animal. PRIMRORR : THR ANATr'MV OP THE ORANO OUTANQ •t the spine of the scapula. A branch of the spinal accessory nerve was traced to the muscle. The shortness of the fibres of the trapezius muscle in that part of it which extended from the spine of the scapula to the occiput, and also of the fibres of the levator anguli scapuhu, has already been noted as accounting to some extent for the shortness of the neck in the Orang. The Latisstmus dorsi arose from the spines of the lower four dorsal vertebra; and the supra-spinous ligament, also from the lumbar apon- eurosis and from the iliac crest extending as far forwards as the anterior superior iliac spinous process. There was thus no " triangle of Petit" as the latissimus dorsi overlapped the external oblique muscle of the abdom- inal wall at its insertion into the iliac crest. The muscle was inserted into the humerus in front of the teres major, but at a .somewhat higher level than that muscle. F'rom the latissimus dorsi, near its insertion, there arose from its tendon a strap-like muscle band (1.5 cm. wide), which pro- ceeded down the arm to be inserted into the fascia attached to the internal condyle and the supra-condyloid ridge of the humerus. This has been called by Bischoff the Latissimo-condyloideus. Another muscular slip derived from the latissimus dorsi passes on a plane posterior to the main part of the muscle, and also behind the slip passing to the internal condyle, to be inserted along with the lower part of the teres major muscle into the humerus. This slip to the teres major muscle was found by Hepburn' in both the Chimpanzee and the Orang- The latissimo-condyloideus or Dorso-epitrocJdearis, as it has been designated by some authors, occurs in all apes, not only in anthropoid apes, but in all apes lower in the scale. It is therefore a characteristic muscle of the ape and is always present in these creatures, whilst in man it is absent, or only occurs occasionally in a very rudimentarj' form. Thus in man one finds that a muscular slip is occasionally given off from the latissimus dorsi and passes downwards to the long head of the triceps, to the fascia, or to the internal intermuscular septum of the ann (Quain^); this, it is claimed, corresponds to the latissimo-condyloideus of the ape. The Rhomboideus muscle in the Orang formed a continuous sheet arising from the dorsal spine as low as the sixth vertebra, and from the ligamentum nuchae, also receiving a very definite slip of origin from the occipital bone — the occipital attachment was 2.5 crn. wide. This occi- pital portion, although showing a continuous line of origin with the part I David Hepburn, " The Compar.ttive Anatomv of the Muscles and Nerves of the Superior and In- ferior Extremities of the Anthropoid Apes," Journ. of Anat. and Phys., Vol. XXVI, 1892, {>. ij>. 3 "Quain's Elements of Anatomy," edited by Schilfer and Thane, Vol. II, part a, i8qi, p. 105, :i'i i-'H \A 32 PRIMROSE : THE ANATOMY OF THE ORANG OUTANG ■ ili 1 ■ ; iiM arising in the middle line of the back, was somewhat separated from the latter by a narrow interval, which is indicated in the drawing (plate III, fig. l,r/iom). The two portions, occipital and spinal, united to form a con- tinuous insertion into the whole of the vertebral border of the scapula, the upper part lying on the dorsal aspect of the levator anguli scapulae where the latter muscle was inserted into the scapula. The occipital origin is not constant in the Orang, as Fick' found that in his specimen the muscle did not arise higher than in man. On the other hand, Bischoff, Owen and others have described an occipital origin in the Orang, and it appears to occur also in the lower apes. Macalister failed to find it in a young female Gorilla dissected by him. There was no occipital attachment described by Duvernoy in the Gorilla.^ In man one finds that the occipital attachment occurs as an occasional variety. The Levator anguli scapulce (plate III, fig. I, La.s.\ arose by three slips from the transverse processes of the upper three cervical vertebrae, and was inserted into the upper angle of the scapula and into its vertebral border, lying there in the deep aspect of the rhomboid muscle. At its insertion it was closely incorporated with the serratus magnus muscle. In an Orang dissected by Fick'* the origin of the muscle extended as low down as the transverse process of the seventh cervical vertebra. The Serratus Magnus arose by eleven digitations from the upper eleven ribs, taking its origin from the anterior extremities of the osseous ribs, and in its lower portion interdigitating with the external oblique muscle of the abdomen. It passed backwards to be inserte. into the whole of the vertebral border of the scapula, blending there with the levator anguli scapulae as already described. The two muscles last described are closely related to one another ; it wi'l be observed that when the levator anguli scapulae arises from the complete series of cervical vertebrae (as in Fick's Orang), the muscle becomes ne;essarily almost continuous at its origin with the serratus magnus, and as we have already observed they are united at their insertion. Thus an almost continuous sheet of muscle is formed. In man the muscles are wholly separate, the one in the neck and the other in the thorax. These observations led Bischoff* to conclude that in the I Loc cit., p. 19. 1 Loc. cit., p, 76. 3 Rudolf Fick, 1. " Beohachtungen an einem zweiten erwachsenen Orang-Utang und einem Schim- panien." Arrhiv fllr Anat. und Phy»., Annt. Abt., 1895. p. »y}. 4 Bischoff, " Beitr^gc zur anatumie des flylobAtes leucisua und ''u einer vergleichenden Anatomic dcr Muskein der AiTen und des Men«;hen." Abhandl. der mat.i.phyn. Claase der kiinig. bayer, Akad. der Wiasenschaften, Vol. X, 1870, p, 207. PRIMROSE : THE ANATOMY OF THE ORANG OUTANG »i d from the (plate III, brm a con- le scapula, uli scapulae le occipital is specimen Other hand, gin in the lister failed ere was no In man nal variety. y three slips ertebrae, and its vertebral iscle. At its ^nus muscle. :le extended il vertebra. n the upper )f the osseous ernal oblique rte. into the ere with the one another ; ises from the ), the muscle the serratus liled at their ; formed. In and the other de that in the f und einem Schim- 9tchenden Anatomic !>nigr. bayer. Akad. ape we had definite proof that the two muscles belong to one another and form one single great muscle going from the ribs in the chest and from the cervical vertebrae in the neck to be inserted into the whole length of the vertebral border of the scapula. Bischofif states that in Macacus and other lower apes, this continuity of the two muscles is even more complete than in anthropoids ; in these a bundle arises from the first rib, which unites immediately with that arising from the seventh cervical vertebra, whilst in anthropoids a space exists between the two portions as a rule. One must remember, however, that the extensive origin described from the cervical vertebrae does not always exist in the Orang, as in my specimen there were only three slips of origin from the three upper cervical vertebrae. Hepburn^ describes four slips in the Orang dissected by him. In man there occasionally occurs partial union between the two muscles in question (Quain), whilst the origin of the levator may be extensi'c;, receiving aponeurotic fibres even from the first and second ribs (Testut). It would therefore appear that, as a rule, the two muscles are distinct in man ; they are continuous in the lower apes, c.nd the higher (anthro- poid) apes occupy an intermediate position where there is a partial con- tinuity. The Omo-cervicalis (plate III, fig. I, m.o), is an interesting muscle which Bischofif asserts is not found in man,^ at all events of similar character to that occurring in apes. It arose in my Orang from the anterior aspect of the arch of the atlas vertebra and from Its transverse process ; it was inserted into the cb.vicle on its posterior aspect at the junction of the middle and outer thirds of the bone, the attachment to Ihe clavicle being 1.5 cm. wide. The muscle has been described in the anthropoid apes and in the lower apes by Huxley,' whilst in the various anthropoids it has been found by Cuvier* Vrolik,' Owen," Chapman,' IVlacalister.' and others. Its attachment to the shoulder girdle varies in apes and I Loc. cit., p. ijj. a Loc, cit,, p 207. ., «. cit., Vol. I, pp. 4j8, 40, sj8, 506, 647. and Vol, 11. p. 40. 4 Georges Cuvier, ''Anatomic compar(ie j recueil de plnnchen de myoiogie, " Pari.i, 1849. 5 Toe. cit., p. 18. 6 R. Owen, " Myology of Simia Satyrus,'* Proceedings .if the ZiHilogical Society r*" London, Part I. '830-31, p. jq. 7 H, C, Chapman, " On the Structure of the Orang-Outang,'' Proceedings of the Academy of Natural Science of Philadelphia, 1880, p. i6i, 8 Alex. Macalister. " The Muscular Anatomy of .he Oorilla,' PruceeJings of the Royal Iriih Academy, Sr, 1, Vol, 1, i87o-,'4, p. 501, ',f' ■1! f 94 PRIMROSE : THE ANATOMY OF THE ORANG OUTANG hence Bischoff suggested the name of " omo-cervicalis " and abandoned the old names of " cleido-cervicalis " and " acromio-trachealis " which had been applied to it. Tyson called it " levator claviculae." Bischoff asserts that in all four anthropoids it always arises from the clavicle, whilst in Cynocephalus it has been found arising from the acromion process and in Macacus from the spine of the scapula. Deniker' de- monstrated the muscle in a foetal Gorilla of the fifth or sixth month of gestation, and in a foetal Gibbon of the seventh or eighth month ; in both instances passing from the atlas vertebra to the clavicle. It would appear that the atlantal attachment of this muscle is very constant in anthropoid apes, although Champneys^ described the dissection ol .i Chimpanzee in which the muscle arose " from the occipital boat in a line with the occipital condyles and was inserted into the acromial or external half of the clavicle anterior to the insertion of the trapezius." Huxley states that in man^ a separate muscle has been seen to pass from the mastoid process to the extremity of the acromion, detached from the trapezius, and representing, to a certain extent, in man the trachelo-acromial. Testut* mentions a muscle described by Gruber under the name of " trachelo-clavicularis imus" arising from the transverse process of the sixth cervical vertebra, and inserted into the clavicle. This Testut considers a variety of the omo-cervicalis. In Quain's Anatomy" is mentioned a detached bundle of the levator anguli scapula; passing from the transverse process of the upper one or two cervical transverse processes to the outer end of the clavicle ; this would apparently represent a true omo-cervicalis in man. We may conclude, therefore, that the muscle in question is found in- variably in the ape, whilst in man it occurs as a very rare variety. The Omo-hyoid muscle was present and possessed similar attach- ments and relations to those in man. The supra-scapular artery and nerve passed over the superior border of the scapula anterior to the omo- hyoid insertion. There was no indication of a transverse ligament which exists over the supra-scapular notch in man. In Pick's" Orang the omo-hyoid was weak and there was no intermediate tendon. I J. Deniker, " Recherches anaiomiquea et embryologiquea sur lea singes .inthropoVdes jeunes et adultes," Archives de Zooloffie exp^ritnentale, Sr. j. Vol. HI. 1885, pp. 125, 131. 1 F. Champney.s, " On the Muscles ,nnj Nerves of the Chimpanzee (Troglodyte* niger) and a CynoocphaluB anubis." Journ. of Aniit. and Phys., Vol. V!, 187a. 3 Loc ctt., Vol. I, pp. 428, 45*' 4 Loc. cit., Vol. I, Part , p. 6v7. J Loc. cIt.. Vol. II. P^it I, p. 108. 6 Loc. cit., I, p. 15, W^' PRIMROSE : THE ANATOMY OF THE ORANG OUTANG m abandoned lis" which ' BischoflF rie clavicle, acromion eniker' de- 1 month of th ; in both It would constant in ection ot a pital bont d into the le insertion rate muscle e extremity anting, to a mentions a >-clavicularis cal vertebra, iriety of the ched bundle rocess of the r end of the lis in man. is found in- 'ariety. lilar attach- r artery and ■ to the omo- se ligament In Pick's" liate tendon. ■opoVdes jeunes et •'tC4 nigcr) and a Bischoff' also remarks upon the fact that the intermediate tendon often fails to develop in the ape; in Bischoffs Orang, however, the whole muscle failed. This authority also refers to an Orang dissected by Alix in which the omo-hyoid arose from the clavicle as well as from the scapula ; this variation in the Orang is of interest, because a similar variation sometimes occurs in man. The total absence of the omo- hyoid is not rare in man ; of this Testut^ has recorded nine cases. Again the absence of either the anterior or posterior belly may occur, :\nd the bony attachment more particularly of its posterior belly is subject to g^eat %i vp.riation in man. Gegenbaur,' after a critical study of the varieties of the omo-hyoid as it occurs in man, and the conditions of its develop- ment met with in the lower animals, concludes that it belongs to a muscle group including in man the sterno-hyoid and stenio-thyroid muscles. These muscles in some animals (reptiles) form a continuous attachment from the sternum, along the clavicle to the scapula. Referring the omo-hyoid to such a group of muscles we can reav'.ily explain the occurrence of the intermediate tendon and the variation in the bony attachments, sometimes to the clavicle, sometimes to the scapula, or it may be to both bones. The Sterno-mastoid had an extensive origin from the mastoid process and the occipital bone, and was inserted by two heads, one into the manubrium sterni on its anterior aspect, and the other into the inner fourt ol the clavicle. Cuvier^ figures the sterno-mastoid in the Orang as , ' o very distinct muscles, the clavicular portion arising from the -: ,.i> be' w the sternal portion and proceeding to its insertion into the la. ''p. In the Gorilla it is usually in two distinct portions, as indeed It ih ■ ['"-o in the other anthropoids. The two portions of the sterno- masto. W inan are separated from one another by a varying interval at their uibertion. The Pectoralis major, consisted of three very distinct portions : — (i) Pars costo-abdominalis (plate IV, fig. 2, p.m. /), which arose from the osseous part of the fifth rib near its sternal extremity, and by an origin 4 c'.n. wide from the aponeurosis of the external oblique muscle of the abdomen. The fibres passed very obliquely upwards and outwards cifid lay on a plane posterior to the other two portions of the muscle. " »« insertion was into the strong fascia over the biceps tendon, and < Loc. cit., I, p. aoj. J Loc. cit., Vol. I. Pt. >, p. 677- 3 C. Uej^enbaur, " Ueber den MuKulu* Omohyo'i'deus und seine SchlUsselbeinvcrbindun^." Morpiiolo- Kischea Jahrbuch, Vol. I, 1876, p. 164. 4 Loc. dt., pinte 15. 'll. !' 4 '■% ao PRIMROSE : THE ANATOMY OP THE ORANG OUTANG extended up to the greater tuberosity of the humerus and the capsule of the joint — the insertion extended further up on the humerus than the other two portions of the muscle. (2) Pars stemo-costalis (plate IV, fig. 2, p.m. 2), arose from the cartilages of the third, fourth, fifth and sixth ribs, and from the adjacent portion of the anterior aspect of the sternum. It was inserted by means of the strong fascia over the biceps tendon into the humerus, the fibres of this portion of the muscle passed almost horizontally fn r n to insertion. It lay intermediate in position between the pais o-abdominaiis and the pars sternalis. (3) The Pars sternalis (plate l /, fig. 2, p.m. j), arose from the anterior surface of the manubrium sterni near its upper margin. There was no attachment to the clavicle. The fibres passed very obliquel}' from above downwards and outwards in front of the other portions of the muscle. The muscle was inserted into the humerus on the anterior aspect of the bone in front of the biceps by an insertion 2 cm. wide, extending further down on the bone than the other portions of the muscle. The three portions of the pect^ralis major were very definitely separated from one another, the intervals being filled in by a large amount of fat. The other three anthropoid apes, according to Bischofif, possess a fourth division of the pectoralis major, viz., a " pars clavicularis " arising from the sternal end of the clavicle, whilst in an Orang dissected bj' Bischoff ' the clavicular portion was, as in my specimen, absent. On the other hand Kick" f"»?crioes a clavicular portion in both Orangs dissected by him, and Bi.>f '.jfiF' found in a second Orang examined by him, a portion of the pcc'-ir^'.lis major arising from the ligaments of the sterno-clavicular joint. Chapman and Owen both failed to find a clavicular portion in the Orang. Bischoff, it may be added, is authority for the statement that the oars clavicularis fails in the lower apes. It would therefor'j appear that the pectoralis major muscle is com- posed of four portions ; this fact is recognized by Testut in describing the muscle in man as consisting of: ist, portion claviculaire ; 2nd, por- tion sternale ; 3rd, portion abdominale ; 4th, portion chondro-costale. The clavicular portiou, which is, as a rule, well developed in man, is I Loc. cit., I. p. ao8. 1 Loc. rit., I, p. 15 and i p. 198. 3 Bischofl, " Beitra^e zur Anatomie dcs Gorilla," Abhand. der math.-phynik, Clai. e der kOnig:. bayer. Akad, der Wissenschaften, Vol. XIII, Abth. 3. MUnchen, 1880, p. 9. 4 Loc. cit., p. 161. J Loc. cit., p. »), 6 Loc. cit.. Vol, I, pt. 1, p. 7». .Kf PRIMROSE : THK ANATOMY OF THE ORANG OUTANG 87 Clab.'e der ktintg:. present only occasionally in the Orang, and is absent in the lower apes. On the other hand, the Gorilla, Chimpanzee, and Gibbon resemble man in the well-developed clavicular portion of this muscle ; in the Gorilla, in fact it is more strikingly developed than in man. One notices in man considerable variation in the width of the interval separating the clavicular portion of the muscle from the remaining part ; according to Testut this may be several centimetres. One is inclined to believe that the portion in the Orang which I have described as the " pars stern- alis" in reality corresponds to the " pars clavicularis" of man (see plate IV, Fig 2^ p.m. j). My reason for coming to this conclusion is that we have in the anterior part of the " pars sterno-costalis " in my Orang a portion corresponding to the " pars sternalis " of man, whilst the wide interval existing in my Orang between the middle and upper portions of the muscle would correspond to the varying interval observed in man between the sternal and clavicular portions of the muscle. It would appear, therefore, that the upper portion of the great pectoral has gra- dually extended its width of attachment, and has also travelled out. wards. At first purely sternal (as in the lower apes) then having a varying degree of clavicular attachment. In the case of Bischoffs Orang, quoted above, the attachment was intermediate in position, namely to the sterno-clavicular joint. One may note that in man the muscle may extend along the clavicle and become incorporated with the deltoid or, on the other hand, in rare cases, the clavicular portion may be absent (Quain). In my Orang a large triangular interval existed between the anterior border of the deltoid and the suoerior border of the pectoralis major and the clavicle ; this space was crossed by the pectoralis minor. In connection with the pectoralis major in man, various anomalous muscles have been described. In a female subject Bryce' has recently reported the following anomalous development of the pectoral sheet. The upper part of the pectoralis major muscle was ill-developed, being represented by a narrow band resembling in fact, very much, the pars sternalis which I have de-icribed in my Orang. He found present also a " sterno-clavicularis " which arose from the side of the manubrium sterni and the second costal cartilage, and was inserted into the clavicle along the inner two-thirds of the bone. A "sternalis" attached partly to the second cartilage and the tendon of the sterno-clavicularis above, and below to the aponeurosis of the external oblique opposite the seventh cartilage, and a "chondro-epitrochlearis" which arose from the outer end „ ii J ■ T. H. Bryce, " Note un a Group of Varieties of the Pectoral Sheet of Muscle." Journ. of An.Tt. iinj Phys., Vol. XXXIV, 1899, P- 7.'- n f^ as PRIMROSE : THE ANATOMY OF THE ORANG OUTANG of the sixth costal cartilag[e running under the lower border of the pec- toraiis major, it passed down the arm and was inserted into the intermus- cular septum two inches above the internal condyle. The Pectoralis ;«i'«, p. 17a. ::iii.i,: -m ^ PRIMROSE : THE ANATOMY OF THE DRANG OUTANG 37 the muscle the fibres were very oblique, arising from the ulna as higli up as the upper portion of the lower fourth, and passing obliquely down- wards and outwards to the radius. The obliquity of the fibres >, as also noted by Fick. The Supinator longiis arose from the supracondyloid ridge of the humerus as high as the middle of the bone, and extended ^'^wn to within 2.5 cm. of the external condyle. It was inserted into the outer aspect of the lower extremity of the radius, including the styloid process, the whole insertion being 2.5 cm. wide. ^n Kick's Orang the insertion began 7 cm. above the styloid process. In the Gibbcu, BischofT found it short, not reaching to the sty1r>id process but inserted into the middle of the bone. A similar condition was found in the Gibbon by Huxley.' In man the muscle has been found inserted as high up as the middle third of the radius. The Supinator brevis and Anconeus were well developed, and re- sembled in their connections and relations the condition found in man, in other anthropoids and in the lower apes. The Extensor carpi rculialis longior arose below the supinator longus from the supra condyloid ridge of the humerus as low as the external condyle. It passed under the annular ligament in company with the short radial extensor and was inserted into the dorso-radial aspect of the base of the second metacarpal bone. The Extensor carpi radialis brevier arose from the common extensor origin from the external condyle, and was inserted into the dorsal aspect of the base of the third metacarpal bone. The two radia' extensors were crossed obliquely by the short and long extensors of the thumb and the extensor ossis metacarpi poUicis ; they resembled in their relations and connections the condition found in man and in the lower oi. . die anthro- poid apes. The Extensor communis digitorum arose from the co ninon extensor origin, and passed under the annular ligament in company with the ex- tensor indicis ; it divided into four tendons for insertion into the four inner digits as in man. The Extensor minimi digiti was a very small fasciv:uliis arising in common with the extensor communis ; it was inserted into the extensor expansion over the proximal phalanx of the ring and the h>*le fingers. One finds that the slip to the ring finger occurs as a variety in man, I Loc. cit., Vol. I, p. 648. -i !■' t •S F 38 PRIMROSE : THE ANATOMV OF THE ORANG OUTANG whilst it would appear to be the usual condition in the Orang, as described by Fick, Bischoff, Huxley, Hepburn and Chapman. On the other hand, according to BischoflF, ' in the Gorilla, Chimpanzee and Gibbon, and in the lower apes (excluding Cynocephalus, where it exists as in the Orang), the tendon is restricted to the little finger as it is in man. The Extensor carpi ulnaris arose from the common extensor origin, from the olecranon process and the posterior portion of the ulna and from the intermuscular septum ; it was inserted into the ulnar border of the fifth metacarpal bone. The Extensor Indicts arose from the middle of the ulna by an origin 1.5 cm. wide, and from the interc.-'^eous membrane, passing beneath the common extensor, it was inserted into the extensor expansion over the dorsal aspect of the proximal phalanx of the second and third digits. In nan the extensor indicis is inserted into the index finger only, although, as a variation, it is not very uncommon to find a slip to the middle, or even the ring fingers, whilst occasionally there is a slip to the thumb. It is sometimes altogether absent in man, and Testut" states that he has seen it tendinous throughout its whole extent. According to Bischoff^ in the Gorilla alone among anthropoids do we find the extensor indicis restricted to the index finger and thus resembling man. In the Orang and Chimpanzee it passes to the second and third digits, whilst in the Gibbon it passes to the second, third and fourth digits. In the lower apes also it would appear to be distributed, as a rule, to the second and third digits. Pithecia being an exception ( BischofT), where it is restricted to the index finger only. Huxley,* in discussing this muscle in the Orang along with the extensor minimi digiti, calls attention to the fact that the normal arrangement in many of the lower mammalia is to have a superficial and a deep extensor supplied to every digit. This arrangement is approached when as in my Orang the extensor miniini digiti is supplied to the fourth and fifth toes, and the extensor indicis to the second and third toes. These two muscles, as they occur in man, are therefore but fragments of a more extensive muscle group occurring in lower animals. The Extensor longus pollicis arose from the dorsal aspect of the ulna above the origin of the extensor indicis, and pa.ssed to its insertion in a I Loc cit. I, p. iia. a Loc. cit. I. Vol. I, pt. J, p. 8i]. y Loc. cit, I, p. jii. 4 Loc cit.. Vol. I, p. 396. PRIMROSE : THE ANATOMY OF THE ORANG OLTANG 39 separate compartment of the annular ligament; it was inserted into the second phalanx of the thumb. The Extensor brevis pollicis arose from the interosseous membrane and from the dorsal aspect of the radius and the ulna, it was inserted into the radial aspect of the base of the first metacarpal bone well to the anterior surface. This muscle is absent in most apes. Langer, Fick, Bischoff, Huxley and Chapman failed to find it in the Orang, whilst Hepburn' describes the muscle as being inserted, as in my example, into the metacarpal bone. Bischoff states that the muscle is absent in all apes, with the exception of the Gorilla. The muscle in my Orang was quite separate from the extensor ossis metacarpi pollicis, and had a distinct and separate insertion into the metacarpal bone. It represents a condition intermediate between that normal in man and that which Testut says is^ constant in most apes where, according to this authority, the short extensor is blended with the extensor ossis metacarpi pollicis. The Extensor ossis tnetacarpi pollicis Mosehom the radius and ulna, the more extensive attachment being to the rr.dius, and was inserted by two tendons, one of which passed to the trapezium and the other to the fascia, from which the abductor pollicis and opponer irose. On the right side Rudolf found this tendon passing to the metacarpal bone of the thumb. On close examination of the slip to the trapezium one found, close to the point of insertion, a small irregularly oval sesa- moid bone about 4 mm. in length. This bone was embedded in fibrous tissue which extended from the styloid process of the radius above to the base of the first metacarpal bone, and was there closely applied to the trapezium immediately below the tubercle of the scaphoid ; the fibres of the tendon of the muscle appeared to be inserted into this bone. The sesamoid bone is described by Fick^ and hy Hepburn* in con- nection with the tendon of the exte isor ossis metacarpi pollicis in the Orang. Fick describes the muscle as inserted into the trapezium and the first metacarpal on the left side, whilst it had an additional insertion into the scaphoid on the right side of his Orang. Bischoff'' states that in the Orang, Cynocephalus, I'ithecia and Hapale, the muscle is inserted as in man, into the metacarpal bone, whilst in the Gorilla, I Loc. dt., p. 167. a Loc. cit. I. Vol. I. pt. 1, p, 8u. 3 Loc. cit. I, p. — , 4 Lnollex rudiment. Born* has examined similar structures in the tarsus of amphibians. In rana esculenta he figures a tarsus in which a supernumerary digit is added on the tibial side of the foot. This consisted of three catilaginous elements .separated by joints and united with a tarsal element which it ihared ivith the first meta- tarsal ; a somewhat similar condition was found in Bufo varir.oilis. Emery' traces various carpal elements in the larvje of amphibia, and describes in the anura what he considers to represent the pra:pollex, and the pnuhallux ; he also demonstrated similar structures in rodents. Menschlichen ■ i^oc. cit., p. 13. 1 O. Thilenius, " Die ' UberziihIiKen ' Carpimelcmente inenschlicher Embryonen." Anatomiacher Anzeigc. ix., 1894, p. 66,v 3 Pfitziier, " Rermerkunffcn zum Aufbau den menschlichen Carpus.*' Verhandlun^en tier Anatomis- chfii I'.fKfllnchaft. GittlinKen, i&ij. p. 186. 4 ti. Born, " l')ie Scch^te Zehe Jcr Anuren." Morpholoijisi-hes J.-ihrbuch, Vol. I, 1876, p. 436. .S C Emery, " Zur Morpholoffie dcs Hand und Fussskcletta." Anatomischer Anzeigrer, iScjo, p. aSy, m 43 PRIMROSE : THE ANATOMY OF THE ORANG OUTANG Baur,' as the result of his investigations of the reptilian carpus, con- cluded that the praepollex element was one of the true carpals (radiale) displaced, being pressed out whilst the radiale centrale had taken its place and appeared as the representative of the true radiale. He con- siders that a similar view may be held regarding the amphibian carpus. Baur thus questions the validity of the praepollex theory. On the other hand, Bardeleben' is one of the strongest exponents of the theory. After studying the subject from the embryological standpoint and examining more than a thousand skeletons in the comparative anatomy collections of Berlin, Leyden, and London, he concludes that we must relinquish the old doctrine of five digits for the mammalia. The argu- ment of Bardeleben is very interesting and ingenious. He finds in one of the Cape rodents (Pedetes capensis) in two skeletons a prjcpollex possessing a nail, and a postminimus in which were two bone.s. He also conducted his investigations among fossil forms and in the oldest fossil mammal in whic'.i the hand skeleton has been preserved he describes a prsepoUex rudiment. This fossil animal Theriodesmus phy- larchus, comes also from South Africa (Nicholson'). The praepollex rudiment in the carpus of Theriodesmus has also been described by Thilenius.* The elements of the praepollex rudiment here, according to this authority, lie on the radial side of the hand, between the scaph- oid, centrale and trapezium. Bardeleben, in his paper, attempts to trace the muscles of the prsepollex and the post minimus, or rather their repre- sentatives, in the pentadactyle type. Thus the palmaris longus in the hand, and the plantaris in the foot, are looked upon as giving evidence of the existence of those supernumerary digits. Among lower animals (as has already been stated for the palmaris longus) these muscles give a varying number of tendons, numbering from three or four to seven, in some animals. Thus Bardeleben states that we have seven tendons representing the termination of the muscle in Centetes (one of the hedge-hog family of Madagascar). One of these tendons went to the praepollex and the other to the postminimus. Similar conditions were found in the plantaris. To the four groups of interossei present in the mammalian hand or foot Bardeleben would add the abductor muscles I G. Baur, " Der Carpus der SchildkriSten," Anatom!scher Anzeiger. 1891, p. jo6. 1 K. Bardeleben, " Ueber die Hand-und Fuss-Muskeh, der SiiuKetiere, beoonders die des Prspotlex (Prchallux) und Postminimus," Anatomisclier / nzeiger, liqo, p. 4jj. 3 A. Nicholson, "A Manual of Palicontolo8:y.'' Edin. and Lond., t88q. Vol. U, p. ij6q. Nicholson's description of this mammal is as follows : — "In the Karoo system of South Africa, in a horizor. which is probably of lower mesozoic ag:e, has been obtained a slab showings the impression of a pectoral limb, appar- ently referable to a small r-.ammal, which has been described under the name of Theriodesmus.^ 4 G. Thilrr'us, "Ueber Seaambcine fossiler SHugetiere." Anatomiicher Anzeiger, 18^-95, p. 41. PRIMROSE : THE ANATOMY OF THE ORANG OUTANG 43 :arpus, con- als (radiale) taken its He con- bian carpus. n the other the theory. dpoint and ve anatomy lat we must The argu- finds in one a praepollex e.s. He also the oldest )reserved he desmus phy- e praepollex lescribed by e, according 11 the scaph- npts to trace r their repre- ongus in the ing evidence nver animals nuscles give our to seven, :ven tendons (one of the went to the iditions were resent in the ctor muscles die des Prapollex I a6o. Nichnlaon's horiior, which is ctoral limb, nppar* tmut.' of the first and last digits. The abductor pollicis, and the abductor hallucis, arising from what he considers to be the rudiments of the prffipollex or prashallux, and the abductor minimi digiti in both hand and foot arising from the postminimus. These abductor muscles together with the so-called " interossei," Bardeleben would designate the " flexores breves profundi." In addition, Bardeleben claims certain of the marginal long muscles as contributing to the praepollex, etc.; among others, the extensor ossis metacarpi pollicis, and flexor carpi radialis acting on the praepollex, and the flexor carpi ulnaris acting on the post minimus rudi- ment. He traces similarly corresponding muscles in the foot. Fick* discovered in man what he believed to be a flexor praepollicis. It arose from the outer margin of the radius near the insertion of the pronator, and as a continuation of the flexor longus pollicis, a portion was inserted into the transverse carpal ligament, but the chief tendon of insertion was attached to the volar projections of the trapezium and the scaphoid, processes which were considered by Pfitzner to represent the pra;tra- pezium, and therefore the prapollex rudiment. Fick places consider- able importance upon the fact that this prspoUex rudiment was still a " rudiment " in the oldest known mammal, and concludes that it is highly improbable, therefore, that the primitive mammal possessed a true praepollex. This fact would also go to disprove the other theory that the praepollex, etc., are secondary new formations. These digits, if they exist, do not appear to have made any progress in development in the mammal Gratiolet and Alix= found the extensor ossis metacarpi pollicis in- serted in the Chimpanzee by two tendons — one into the trapezium and the other into the base of the first metacarpal. In a foot note these authors refer to the fact that no sesamoid bone was present in Lh»; slip to the trapezium, and its absence they attribute to the iav:t that the animal was young. The explanation is not valid, as the bone was present in my Orang, although it was a young specimen. The Abductor pollicis (plate V, fig.jakp.) muscle wa well developed; it arose from the trapezium and the annular W^aw ., and was inserted into the radial bord'^r of the proximal phaianx of the thumb. The muscle would appear to present very few variatiosis in the ape from the condition found in man. In Hepburn's Orang it arose fn.m the annular ligament and had no direct attachment to the carpal bones. The Opponens pollicis arose from the trapezium and the annular A T|r— I Loc, cit . , p. a?. a Loc. cil.. p. 163. 44 PRIMROSE : THE ANATOMY OF THE ORANO OUTANG ligament, and from the tendon of the extensor ossis metacarpi poUicis, and was inserted into the radial border of the first metacarpal bone. Brooks' also described the origin from the extensor ossis metacarpi pollicis. The opponens is well developed in apes and resembles in attachment and development the same muscle in the human hand. The Adductor obliqutis pollicis arose from the bases of the second and third metacarpal bones and the ligaments over the anterior surface of the carpus. A portion of the adductor obliquus pollicis (indicated in plate V, fig. 5 a.ob.p.) exists as a separate slip passing over the anterior surface of the metacarpal bone. This apparently corresponds to the muscle and tendon fasciculus which Langer'- describes and figures, and which he believes to represent the flexor longus pollicis of man ; it is in conse- quence of the existence of this muscular slip that the Orang is capable of bending the terminal phalanx of the thumb. The Adductor transverstis pollicis arose from the base of the third metacarpal bone and the distal extremity of the second metacarpal bone, and from the fascia over the interossei muscles between the two bony points named. The adductor muscles of the thumb in the Orang thus correspond very clc 'v to the muscles of the same group in the human hand. The Flexor brevis pollicis. The inner head of the muscle (the " inter- osseus primus volaris" of Henle, plate V, ^%. 5 f.bp.2) arose from the base of the first metacarpal bone, and was inserted into the base of the first phalanx with the adductor obliquus pollicis. The outer head of the flexor brevis pollicis (plate V, fig. 5 f.h.p. /), arose from the anterior annular ligament and was inserted into the radial portion of the base of the proximal phalanx. Flemming' looked upon the flexor brevis pollicis as a single headed muscle. This view has been proved to be incorrect by Cunninghani' who holds that in the foot as in the hand the flexor brevis of the first digit is always a double headed muscle, and man is no exception to the rule. In man the ulnar head has suffered diminu- tion and has been suppressed by the great development of the adductor. The inner head is the muscle which Henle called the " interosseus primus volai is." It was Bischoff who first enunciated the view that such was the case in demonstrating the true significance of the interosseus I Loc. cit., p. 8a. 3 Loc. cit, p. 183. 3 W. Flemming^, "Ueber den Flexor brevU pollicis und hallucis dea Menachen." Anatomischer Anzeiger, 1887, pp. 68, i6q. 4 D. J. Cunningham, "The flexor brevis pollicis and the flexor brevis hallucis in man,' iscber Anzeiger, i89i, p. ao6. Anatom- ff PRIMROSE : THK ANATOMY OF THE ORANG OUTANG 45 primus volaris of Henle, and Cunningham confirms him in every par- ticular. In the case of the foot Flemming advanced an argument based upon the nerve supply, but his argument fails, because Cunningham has shown that Flemming followed Henle and Schwalbe in describing the nerve supply of the fibular head to be from the external plantar nerve, whilst throughout the entire class of the mammalia Cunningham has only once found this head thus supplied [i.e., in the fox-bat), with this ex- ception it is always supplied by the internal plantar, as is the tibial head. Even if Flemming were right regarding the nerve supply Cunningham holds that the point would not afford sufficient proof, as it has been shown that where tvo nerves approach one another,a tendency to variation in the supply to muscles occurs when they reach the confines of their distribution. Cunningham states that in only one instance was he able to trace the nerve supply of the interosseus primus volaris in the hand, and in that instance it appeared to come from the deep branch of the ulnar. The Abductor minimi digiti (plate V, fig. 5 ab.m.d\ arose from the pisiform bone and the annular ligament, and was inserted into the base of the first phalanx of the little finger on its ulnar side. The Flexor brevis minimi digiti (plate V, f\g, ^ fl.b.m.d.) arose from the unciform bone and the annular ligament, and was inserted into the base of the first phalanx of the fifth digit on its ulnar side. In Fick'i: Orang a second head arose from the palmaris longus tendon. The Opponens minimi digiti (plate V, fig. 5 op.m.d.) arose from the unciform bone and the annular ligament, and was inserted into the whole length of the metacarpal bone of the little finger. The short muscles of the thenar and hypothenar eminences have a grea.er or less extension of their fibres of insertion beyond the bony points already described, and blend with the extensor aponeurosis on the dorsal aspect of the digits. In this respect they resemble the interossei, and Langer would, from this circumstance, argue in favour of the theory that these muscles are modified interossei. The Orang would appear to have a greater development of thumb muscles than obtains in the hand of man as far as the development of those muscles which act upon the metacarpal bone is concerned, but the movements of the terminal phalanx are obviously very weak, the flexor longus poUicis being absent or extremely rudimentary. Further, it would appear that adduction to the index is the most powerful move- ment attainable, as judged from the development of the muscles. The I Loc. cit., p. 184, I • 4 'W •14 46 PRIMROSE : THE ANATOMY OF THE ORANG OUTANG flexor brevis pollicis is also well developed, probably better than in man, and thus flexion of the first phalanx can be well accomplished. The inner head of the flexor brevis resembles that in man in being very feebly developed, and in being completely pressed into the deeper parts and covered over by the adductor obliquus, and according to Bischoff' a similar condition is found in the Gibbon. In the Gorilla, Bischoff' was unable to separate the outer head of the flexor brevis from the opponens, or the inner head from the adductor obliquus. It would appear from reference to the records of various authorities, that whilst great varia- tions exist among apes in the degree of development of the short mus- cles of the thumb, they are nevertheless all represented in the different species. Even in the spider monkey (Ateles) according to Huxley, in which the thumb is functionless, being wholly rudimentary and buried under the skin, all the muscles, abductors, adductors, short flexors and opponens are present, the long flexor alone of the muscles usually found in this situation being absent. A variation sometimes occurs according to Fick' and others, in the insertion of certain fibres of the adductor into the shaft of the metacarpal bone of the thumb, thus con- stituting a second opponens. The Interossei (plate V, figs. 6 and 7). The first dorsal interosseous muscle arose from the ulnar side of the base of the first metacarpal by one head, whilst the other head arose from the dorsal, radial and palmar surfaces of the second metacarpal bone. The second dorsal interos- seous arose from the ulnar half of the dorsal surface of the second metacarpal bone, and from the dorsal, radial and palmar aspects of the third metacarpal. The third dorsal interosseous arose from the radial half of the dorsal surface of the fourth metacarpal, and from the dorsal, ulnar and palmar aspects of the third metacarpal. The fourth dorsal interosseous arose from the radial half of the dorsal surface of the fifth metacarpal, and from the dorsal ulnar, and palmar aspects of the fourth metacarpal bone. The palmar origins of the dorsal interossei, above described, were in all instances particularly well developed, forming in fact larger fasciculi than those arising from the dorsal region. On the palmar aspect of the third metacarpal bone the palmar origins of the second and third interossei meet together over the proximal half of the bone. The muscles were inserted as in man. 1 Loc. cit. I, p. 315. a Loc. cit, 2, p. 16. 3 Loc. cit. 3, p. 303, rT PRIMROSE : THE ANATOMY OF THE ORANG OUTANO 47 The palmar interossei arose each by a single head from the meta- carpal bone of the di^it upon which it acts. The first palmar inter- osseous muscle arose from the palmar and ulnar surfaces of the second metacarpal, whilst the second and third palmar interossei arose from the palmar and radial surfaces of the fourth and fifth metacarpal bones respectively. They were inserted as in man. The drawings (plate V) are faithful representations of the relations which existed, and one has reproduced in a diagrammatic fashion in fig. 4, plate IV, the relations of the intercssei to the metacarpal bones as they appear in transverse section. The second, third and fourth metacarpal bones were thus completely surrounded by the interossei in the proximal two-thirds of their length. Bischoff described' the interossei very fully in a large number of the lower apes and the anthropoid apes. He recognized the fact that there existed a palmar set of interossei as distinct and independent muscles. They vary in the number present in the different apes, but never exceed three, and were always developed in connection with the second, fourth and fifth digits. The double insertion of the various interossei, both palmar and dorsal, whereby they are on the one hand attached to the base of the proximal phalanx and on the other into the extensor aponeurotic expansion on the back of the phalanx, was first pointed out by Huxley' in anthropoid apes. The interossei and their attachments were fully described by Huxley in all four anthropoids. Bischoff found the interossei in the Gorilla developed as in man.' The palmar portions of the dorsal interossei formed such very definite structures in my Orang that they attracted special attention. This segment of the dorsal interosseous muscle in fact resembles a palmar interosseous muscle, but this ventral segment is blended very intimately with the dorsal in the tendon of insertion of the muscle. The palmar interossei on the other hand remain independent structures through- out. This condition is very similar to that found in man, and, obviously, the description in most text books of human anatomy regarding these muscles is faulty. Gegenbaur/ however, describes and figures them in tlieir correct relations. Hepburn' apparently found these ventral seg- ments of the dorsal interossei, and, if I read his description aright, looked I Loc. cit. I, pp. 216, 334. I Loc, cit., Vol. I, p. 456. 3 Loc. cit 3, p 17. 4C. Gcg^enb.iiir, " Lchrbuch Jer All.^toIniellcs Meiischen." Leipzig;. Vol. I, p. 431, fig. 303. S Loc. cit., p. 174. r . •V ^^ ■ 1 • \ '■>. %■ * W '* , t .1 I- 48 PRIMROSE : THE ANATOVV OF THE ORANG OUTANO upon them as additional palmar interossei.and thus described six palmar interossei in the Chimpanzee instead of three. From one point of view Hepburn would appear to be justified in classing these ventral segments of the dorsal interossei with the palmar interossei, and this whole group of six mus<;les, as represented in my Orang, (plate V, figs, 6 and 7) might be referred to the intermediate layer of Cunningham which that author describes as constituting the " flexores breves." We shall return to the discussion of the interossei after describing the muscles of the foot. In the dissection of the muscles of the lower extremity one found the fascia lata poorly developed, as compared with the similar structure in man. The Gracilis arose from the body of the pubis by an origin 3.5 cm. wide, immediately external to the symphysis and corresponding in width of attachment to the depth of the symphysis. It did not extend to the descending ramus of the pubis ; it was inserted into the inner aspect of the tibia by an expanded aponeurosis of insertion 3 cm. wide. The upper limit of the insertion is 3 cm. below the articular surface of the tibia. It forms a flat ribbon-like muscle varying in width from 2 cm. near its origin to i cm. near its insertion, and was supplied by the obturator nerve. Fick remarks on the strong development of this muscle in the Orang, and »iso observed the absence of any origin from the pubic ramus. The Sartorius, a very poorly developed muscle, arose from the ilium below the anterior superior spine, and was inserted into the inner surface of the tibia, above and anterior to the insertion of the gracilis. This muscle was only about one-fifth the size of the gracilis, and was supplied by the anterior crural nerve. On the right side Rudolf found that the muscle divided into two tendons of insertion, the anterior being inserted into the inner aspect of the tibia in the position indicated above for the left side, the posterior joined with the fascia around the knee joint. Between these two portions passed an artery of considerable size, which was found to arise from the femoral one inch above the knee, and run down the inner side of the leg to the cleft between the first and second toes, where it disappeared between the heads of the first dorsal interosseous muscle; a vein accompanied the artery and entered the femoral vein one inch above the knee. Fick' described an artery, the arteria genus suprema, in the Orang as a large vessel as thick as the pro- funda arising above the knee and extending with the saphenous nerve I Loc. cit. I, p. 35. .1 I-l PRIMR08B : THE ANATUMV OF THE ORANG OUTANO palmar oint of ventral ind this ; V, figs, iiingham ;s." We jing the )und the jcture in n 3.5 cm. nding in extend to ler aspect le. The ce of the •om 2 cm. d by the It of this •igin from I the ilium the inner he gracilis. 1, and was dolf found srior being ated above 1 the knee erable size, J knee, and e first and first dorsal entered the artery, the as the pro- jnous nerve to the dorsum of the foot. The sartorius muscle i*; usually very feebly developed in he anthropoid apes as compared with man. Gegenbaur states' that the sartorius is as well developed in the anthropoid apes as it is in man, but this is by no means invariably the case — in my Orang it was very rudimentary, and Fick found it .so also in the same animal. Hi.scho(if, too, and Duvernoy' state that the muscle is weak in the Gorilla, whilst Gratiolet and Alix' found it weakly developed \n . i Chimpanzee. The attachment of the sartorius to the inner side of the knee joint, similar to that found by Rudolf, has been described in man (Testut). The Adductor longus arose from the inner portion of Poupart's ligament and from Gimbernat's ligament and from the pubis extending I cm along the bone on the superior part of the horizontal ramus immediately external to the pubic spine ; it was inserted into the inner aspect of the femur, the line of in.sertion being 1.5 cm. long, the lower limit of this line being only 2 cm. above the internal condyle, i'l e Pectineus, lying in the same plane as the adductor longus at its origin, arose from the horizontal ramus of the pubis, the origin being i cm. wide, continuous there with the adductor longus as it passes back- wards and downwards, wrapping itself around the shaft of the femur, and was inserted into the posterior aspect of the femu: at the junction of the middle and upper thirds, the insertion being 2.5 cm. wide. The Adductor brevis arose from the pubis immediately beneath the adductor longus, by an origin 1.5 cm. wide ; it was inserted into the posterior aspect of the femur on a plane posterior to that of the pectineus. The muscle was supplied by the obturator nerve. The Adductor magnus, a large bulky muscle, arose from the pubic bone opposite the whole extent of the symphysis immediately subjacent to the gracilis, and on the same plane as the adductor brevis at its origin. The attachment of origin extends back along the descending ramus of the pubis and the ascending ramus of the ischium to within i cm. of the tuberosity of the ischium. The lower, or inner border was thick f.nd rounded, whilst the upper (or outer) was thin and attenuated. The lower part of the muscle was inserted by a rounded tendon into the internal condyle of the femur, the lowest fibres passing to the internal lateral ligament of the knee joint. The muscle above this point is inserted into the posterior aspect of the femur in a plane posterior to the I Loc. cit.. (Lehrbuch) Vol. I, p. 439. 1 Loc. cit., p. 90. 3 Loc. cit., p. 186. .1 'I so P."