I admit that if I were to take into account all the individual differences of the gorilla skulls and skeletons of the same sex and of about the same age, I should be able to produce a half-dozen or more species of gorillas. I have observed such differences in the case both of male and female individuals of about the same age, and have given an exact description of them in my osteological work on the gorilla to which I have so often referred. I cannot, however, refrain from regarding these differences as of a purely individual character. Much in the description by Alix and Bouvier--as, for instance, their remarks on the comparative smallness of the head, on the slenderness and smoothness of the limb bones--appears to me to point to the youthfulness of this Landana specimen. The unlearned may be struck by what is said of the small spinous processes of the upper cervical vertebræ in this specimen, but in the common gorilla the processes of the three upper vertebræ are also small (see Fig. 17). Individual and sexual variations in the general development of the cervical spines may be observed, not only in this case, but in the chimpanzee, and even in man. I think it very doubtful whether a characteristic of species can be founded only or chiefly on this distinction. What is said of the colouring of the coat of the so-called new species appears to me still less worthy of consideration. I have spoken above in detail of the many individual varieties of the colour of the hair in different specimens of gorillas. I have also observed long, thick hair, not always short, scanty, and worn away, on the backs of many gorillas of different sexes. The condition described by Alix and Bouvier must refer to the hides of aged and sickly animals, or to those younger individuals affected by the kind of mange which is widely diffused in Africa. Every gorilla delights to rub his back against the trunk of a tree, and leans against it in a contented mood, and so also does the chimpanzee. This is the habit of many other mammals, such as cats, lions, boars, deer, and elephants. Man himself will sometimes adopt such an attitude. Without more convincing proofs that _Gorilla Mayema Alix et Bouvier_ constitutes a distinct species, I should prefer to leave the matter in suspense.