The vascular system of anthropoids has not up to this time been studied in any exhaustive manner. The heart strongly resembles that organ in man. In the gorilla, the chimpanzee, and the orang the great arterial branches have the same relative conditions as in the human organism. A common origin from one branch of the subclavian artery, and of the right and left carotid arteries, often occurs in the orang and with a certain constancy in the gibbon, so far as we can judge from the researches which have been made up to this time. But we know that this form of deviation from the common type is not altogether rare in man. Bischoff and others have justly maintained that the resemblance to man which is found in these animals in the arrangement of the heart and larger blood-vessels appears to be connected with their mode of life. For although their habits are arboreal, this very fact implies that they are for the most part in an upright position. The division of the femoral arteries displays a somewhat interesting deviation from the normal human type. High up near the femoral arch an artery, accompanied by veins and a large nerve, diverges from the femoral artery, which extends, together with its accompanying parts, as far as the back of the foot. In the gorilla this branch pierces the sartorius. CHAPTER IV. ON VARIETIES IN THE FORM OF ANTHROPOIDS. Up to recent times it was generally supposed that there was only one species of gorilla, and the differences in the structure of the skeleton and of the external body which were observed in the several specimens under examination, were either regarded as the expression of a purely individual variation or as due to differences in age and sex. Not long ago Alix and Bouvier obtained from Landana on the Congo the skeleton and skin of an aged female gorilla, which had been killed by Lucan and Petit in the village of the negro chief Mayema, on the Kuilu river in 4° 35′ south latitude. This specimen was of less bulk than the common gorilla (_Gorilla Gina_), and its head was comparatively small. The occipito-temporal crest, or transverse crest of the occiput, was much more strongly developed in this animal and the temporal fossæ were deeper. That part of the skull which extends behind the supra-orbital arches was narrower, and so also was the space between the eyes. The keel-shaped prominence rising in the centre of this space is more marked, the nasal bones are arched and not flattened, the orbital aperture is larger in comparison with the general size of the skull, and the frontal processes of the malar bones are wider and more arched. One interesting characteristic consists in a small, vertical, styloid prominence on the posterior surface of the orbital process. On the vertebral column the spinous processes of the first, second, and third cervical vertebræ are only slightly developed in height, while the spinous processes of the three lower cervical vertebræ are as high