| OCR Text |
Show 1905.] BRAIN OF THE BLACK APE. 23 with another, this time of a male and of about twice the size of the former brain. More exact measurements are as follows :- $ brain. $ brain. Length of hemispheres ............... 63 mm. 83 mm. Length of occipital lobe ................10 mm. 24 mm. Mesial end of fissure of Rolando to front end of brain ................36 mm. 48 mm. Greatest breadth of hemispheres 52 mm. 65 mm. On again studying the smaller brain, I cannot find that my description and figures are inaccurate. There remain, so far as that brain is concerned, all the points of resemblance to Semno-pithecus which I indicated in the paper which I have already referred to. The second brain is so strikingly different from the first, that it obviously occurred to me that error might have crept in. Instances of a confusion of labels and bottles are not unknown in Zoology. But a revision of the collection in the Prosectorium appears to disprove this. The second brain, in fact, shows no resemblances to the Semnopitheci in any of the points in which the first brain undoubtedly does. As to the size, in the first place it is necessary to note that the smaller female brain was preserved in alcohol, the effect of which is to cause the brain to shrink and diminish in size; the larger brain, on the other hand, was preserved in formol, which swells out the brain. I found it impossible to refit this brain into the skull. Thus the difference in size between the two brains must be discounted on both sides. They are in reality more nearly equal than would appear from the above measurements. Nevertheless, there still remains a considerable difference, which must imply a difference in age, if not due to sex. The brain upon which I report here is that of a nearly adult male. The permanent dentition is complete save for the last upper molars, which have not quite reached the level of the other teeth. The brain is quite like that of other Baboons. The occipital lobes are smooth above except for the lateral occipital fissure and for the front limb of the T-shaped calcarine fissure which appears upon the upper surface of the brain. The inferior occipital sulcus is not small, as in the first described brain of this species; it is quite Macacine in extending right round to the posterior face of the occipital lobe. The collateral sulcus is concealed, as in Macaques, by the cerebellum. The inferior temporal sulcus is represented, as in Macaques, by a deep furrow at the lower end of the temporal lobe; there is also an upper piece which does not join the inferior occipital sulcus. The Sylvian fissure in this brain does join above (on the right side only) the parallel fissure; this is a common character in Macaques, but certainly rare in Semnopitheci. The original brain of Cynopithecus agreed in this particular with the Semnopitheci. |
