1905-J 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. <J 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 36mm. 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 ah^eady 

 referred to. The second brain is so strikingly difiei-ent 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 Semno- 

 pitheci 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 efiect of 

 which is to cause the brain to shrink and diminish in size ; the 

 lai'ger brain, on the other hand, was preserved in formol, which 

 swells out the brain. 



I found it impossible to refit this bi-ain into the skull. Thus 

 the diflerence 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 measvirements. ISTevei-theless, there still 

 remains a considerable difference, which must imply a difi'erence 

 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 posteidor 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 pai'allel ' fissure ; this is a common character in 

 Macaques, but certainly rare in Semnojntheci. The oiiginal brain 

 of Cynopithecus agreed in this particular with the Semnojntheci. 



