which retains throughout life so much more of the characters of immaturity, especially in the structure of the skull.

The siamang and other gibbons have smaller lower but longer upper canines, relatively, than in the orangs and chimpanzees; the permanent ones more quickly attain their full size, and are sooner in their place in the jaws; consequently the last molar teeth-what we call the 'wisdom-teeth'-come last into place as they do in the human species. But, if this be interpreted as of importance in determining the relative affinity of the longer-armed and shorterarmed apes to man, it is a character in which, as in their seeming superior cerebral development, the Hylobates agree with some much lower Quadrumana with still smaller canines. The comparative anatomist, pursuing this most interesting comparison with clear knowledge of the true conditions and significance of a globular cranium and small jaws within the quadrumanous order, turns his attention to the true distinctive characters of the human organization.

In respect to the brain, he would look not so much for its relative size to the body, as for its relative size in the species compared one with another in the same natural group. He would inquire what quadrumanous animal shews absolutely the biggest brain? what species shows the deepest and most numerous and winding convolutions? in which is the cerebrum largest, as compared with the cerebellum? If he found all these characters highest in the gorilla, he would not be diverted from the just inference because the great size and surpassing physical power attained in that species masked the true data from obvious view.

The comparative anatomist would look to the cæcum and the ischial integument: if he found in one subject of his comparisons (Troglodytes) a long 'appendix vermiformis cæci,' as in man, but no 'callosities,' and in another subject (Hylobates) the ischial callosities but only a short rudiment of the cæcal appendix, he would know which of the two tailless apes were to be placed next 'the monkeys with ischial callosities and no vermiform appendix,' and which formed the closer link toward man. He would find that the anthropoid intestinal and dermal characters were associated with the absolutely larger and better developed brain in the gorilla, chimpanzee, and orang; whilst the lower quadrumanous characters exhibited by the cæcum and nates were exhibited by the smallerbrained and longer-armed tailless gibbons.

Pursuing the comparison through the complexities of the bony

framework, the comparative anatomist would first glance at the more obvious characters; and such, indeed, as would be given by the entire animal. The characteristics of the limbs in man are their near equality of length, but the lower limbs are the longest. The arms in man reach to below the middle of the thigh; in the gorilla they nearly attain the knee; in the chimpanzee they reach below the knee; in the orang they reach the ankle; in the siamang they reach the sole; in most gibbons the whole palm can be applied to the ground without the trunk being bent forward beyond its naturally inclined position on the legs. These gradational differences coincide with other characters determining the relative proximity of the apes compared with man. In no quadrumana does the humerus exceed the ulna so much in length as in man; only in the very highest and most anthropoid, viz. the gorilla and chimpanzee, does it exceed the ulna at all in length; in all the rest, as in the lower quadrupeds, the fore-arm is longer than the arm.

The humerus, in the gorilla, though less long, compared with the ulna, than in man, is longer than in the chimpanzee; in the orang it is shorter than the ulna; in the siamang and other gibbons it is much shorter, the peculiar length of arm in those 'long-armed apes' is chiefly due to the excessive length of the antibrachial bones.

The difference in the length of the upper limbs, as compared with the trunk, is but little between man and the gorilla. The elbow-joint in the gorilla, as the arm hangs down, is opposite the 'labrum ilii,' the wrist opposite the 'tuber ischii;' it is rather lower down in the chimpanzee; is opposite the knee-joint in the orang; and opposite the ankle-joint in the siamang.

Man's perfect hand is one of his peculiar physical characters; that perfection is mainly due to the extreme differentiation of the first from the other four digits, and its concomitant power of opposing them as a perfect thumb. An opposable thumb is present in the hand of most Quadrumana, but is usually a small appendage compared with that of man. It is relatively largest in the gorilla. In this ape the thumb reaches to a little beyond the base of the first phalanx of the fore-finger; it does not reach to the end of the metacarpal bone of the fore-finger in the chimpanzee, orang, or gibbon; it is relatively smallest in the last tailless ape. In man the thumb extends to or beyond the middle of the first phalanx of the fore-finger. The philosophical zoologist will see great significance in the results of this comparison. Only in the gorilla and chimpanzee are the carpal bones eight in number, as in man; in

the orangs and gibbons they are nine in number, as in the tailed monkeys.

The scapula are broader in the gorilla than in the chimpanzee, orang, or long-armed apes; they come nearer to the proportions of that bone in man. But a more decisive resemblance to the human structure is presented by the iliac bones. In no other ape than the gorilla do they bend forward, so as to produce a pelvic concavity; nor are they so broad in proportion to their length in any ape as in the gorilla. In both the chimpanzee and orang the iliac bones are flat, or present a concavity rather at the back than at the forepart. In the siamang they are not only flat, but are narrower and longer, resembling the iliac bones of tailed monkeys and ordinary quadrupeds.

The lower limbs, though characteristically short in the gorilla, are longer in proportion to the upper limbs, and also to the entire trunk, than in the chimpanzee; they are much longer in both proportions and more robust than in the orangs or gibbons. But the guiding points of comparisons here are the heel and the hallux (great toe or thumb of the foot).

The heel in the gorilla makes a more decided backward projection than in the chimpanzee; the heel-bone is relatively thicker, deeper, more expanded vertically at its hind end, besides being fully as long as in the chimpanzee: it is in the gorilla shaped and proportioned more like the human calcaneum than in any other ape. Among all the tailless apes the calcaneum in the siamang and other gibbons least resembles in its shape or proportional size that of man.

Although the foot be articulated to the leg with a slight inversion of the sole it is more nearly plantigrade in the gorilla than in the chimpanzee. The orang departs far, and the gibbons farther, from the human type in the inverted position of the foot.

The great toe which forms the fulcrum in standing or walking is perhaps the most characteristic peculiarity in the human structure; it is that modification which differentiates the foot from the hand, and gives the character to his order (Bimana). In the degree of its approach to this development of the hallux the quadrumanous animal makes a true step in affinity to man.

The orang-utan and the siamang, tried by this test, descend far and abruptly below the chimpanzee and gorilla in the scale. In the orang the hallux does not reach to the end of the metacarpal of the second toe; in the chimpanzee and gorilla it reaches to the end of the first phalanx of the second toe; but in the gorilla the hallux

is thicker and stronger than in the chimpanzee. In both, however, it is a true thumb, by position, diverging from the other toes, in the gorilla, at an angle of 60° from the axis of the foot.

Man has 12 pairs of ribs, the gorilla and chimpanzee have 13 pairs, the orangs have 12 pairs, the gibbons have 13 pairs. Were the naturalist to trust to this single character, as some have trusted to the cranio-facial one, and in equal ignorance of the real condition and value of both, he might think that the orangs (Pithecus) were nearer akin to man than the chimpanzees (Troglodytes) are. But man has sometimes a thirteenth pair of ribs; and what we term 'ribs' are but vertebral elements or appendages common to nearly all the true vertebræ in man, and only so called, when they become long and free. The genera Homo, Troglodytes, and Pithecus, have precisely the same number of vertebræ : if Troglodytes, by the development and mobility of the pleurapophyses of the 20th vertebræ from the occiput seem to have an additional thoracic vertebra, it has one vertebra less in the lumbar region. So, if there be, as has been observed in the same genus, a difference in the number of sacral vertebræ, it is merely due to a last lumbar having coalesced with what we reckon the first sacral vertebra in man.

The thirteen pairs of ribs, therefore, in the gorilla and chimpanzee are of no weight, as against the really important characters significative of affinity with the human type. But, supposing the fact of any real value, how do the advocates of the superior resemblance of the gibbon's skeleton to that of man dispose of the thirteenth pair of ribs ?

In applying the characters of the skull to the determination of the important question at issue those had first to be ascertained by which the genus Homo trenchantly differs from the genus Simia, of Linnæus. To determine these osteal distinctions I have compared the skulls of many individuals of different varieties of the human race together with those of the male, female, and young of species of Troglodytes, Pithecus, and Hylobates; the detailed results of which comparisons will be found in the Catalogue of the Osteological Series in the Museum of the Royal College of Surgeons, 4to, 1853. In the present Appendix, I restrict myself to a few of these results.

The first and most obvious differential character is the globular form of the brain-case, and its superior relative size to the face, especially the jaws, in man. But this, for the reasons already assigned, is not an instructive or decisive character, when

comparing quadrumanous species, in reference to the question at issue. It is exaggerated in the human child, owing to the acquisition of its full, or nearly full size, by the brain, before the jaws have expanded to lodge the second set of teeth. It is an anthropoid character in which the quadrumana resemble man in proportion to the diminution of their general bulk. If a gorilla, with milkteeth, have a somewhat larger brain and brain-case than a chimpanzee at the same immature age, the acquisition of greater bulk by the gorilla, and of a more formidable physical development of the skull, in reference to the great canines in the male, will give to the chimpanzee the appearance of a more anthropoid character, which really does not belong to it; which could be as little depended upon in a question of precise affinity as the like more anthropoid characters of the female, as compared with the male, gorilla or chimpanzee.

Much more important and significant are the following characters of the human skull :-the position and plane of the occipital foramen; the proportion and size of the condyloid and petrous processes; the mastoid processes, which relate to balancing the head upon the trunk in the erect attitude; the small premaxillaries and concomitant small size of the incisor teeth, as compared with the molar teeth. These characters relate to the superiority of the psychical over the physical powers in man. They govern the feature in which man recedes from the brute; and to them may be added the prominence of the nasal bones in most, and in all the typical, races of man. The somewhat angular form of the bony orbits, tending to a square, with the corners rounded off, is, likewise, a good human character of the skull; which is difficult to comprehend as an adaptive one, and therefore the better in the present inquiry. The same may be said of the production of the floor of the tympanic or auditory tube into the plate called 'vaginal.'

Believing the foregoing to be sufficient to test the respective degrees of affinity to man within the limited group of quadrumana to which it is now proposed to apply them, I forbear to cite the characters of minor importance. The question at issue is, as between the anthropoid apes and man. Cuvier deemed the orang

(Pithecus) to be nearer akin to man than the chimpanzee (Troglodytes) is. That belief has long ceased to be entertained. I proceed, therefore, to compare the gorilla, chimpanzee, and gibbon, in reference to their human affinities.

Most naturalists entering upon this question would first look to the premaxillary bones, or, owing to the early confluence of

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