At a late meeting of the British Association (1862), Professor Owen read a paper "On the brain and limb characters of the Gorilla as contrasted with those of Man"* in which, he observes, that in the gorilla the cerebrum "extends over the cerebellum, not beyond it."
(* Medical Times and Gazette" October 1862 page 373.)
This statement, although slightly at variance with one published the year before (1861) by Professor Huxley, who maintains that it does project beyond, is interesting as correcting the description of the same brain given by Professor Owen in that year, in a lecture to the Royal Institution, in which a considerable part of the cerebellum of the gorilla was represented as uncovered.*
(* "Athenaeum" Report of Royal Institution Lecture, March
23, 1861, and reference to it by Professor Owen as to
Gorilla, ibid. March 30 page 434.)
In the same memoir, it is remarked that in the Maimon Baboon the cerebrum not only covers but "extends backwards even beyond the cerebellum."*
(* For Report of Professor Owen's Cambridge British
Association paper see "Medical Times" October 11, 1862 page
373.)
This baboon, therefore, possesses a posterior lobe, according to every description yet given of such a lobe, including a new definition of the same lately proposed by Professor Owen. For the posterior lobe was formerly considered to be that part of the cerebrum which covers the cerebellum, whereas Professor Owen defines it as that part which covers the posterior third of the cerebellum, and extends beyond it.
We may, therefore, consider the attempt to distinguish the brain of Man from that of the ape on the ground of newly-discovered cerebral characters, presenting differences in kind, as virtually abandoned by its originator, and if the sub-class Archencephala is to be retained, it must depend on differences in degree, as, for example, the vast increase of the brain in Man, as compared with that of the highest ape, "in absolute size, and the still greater superiority in relative size to the bulk and weight of the body."*
(* Owen, ibid. page 373.)
If we ask why this character, though well known to Cuvier and other great anatomists before our time, was not considered by them to entitle Man, physically considered, to claim a more distinct place in the group called Primates than that of a separate order, or, according to others, a separate genus or family only, we shall find the answer thus concisely stated by Professor Huxley in his new work, before cited:—