SCIENCE. 



327 



fissures and the ascending branches of the calloso- 

 marginal, is well defined. The lower parietal lobule in 

 the Orang divides naturally into the supra-marginal and 

 angidar gyri. The supra-marginal fold curves around 

 ihe upper end of the posterior branch of the fissure 01 

 Sylvius and runs into the superior temporal gyrus. The 

 angular gyrus, which is very evident, arches around the 

 first temporal fissure, and becoming continuous with the 

 second occipital fold, passes then into the upper temporal 



gyrus. The occipital lobe, separated from the parietal, 

 internally, by the parieto-occipital fissure, is continuous 

 with ihe upper parietal lobule through the first occipital 

 gyrus, and by the second occipital gyrus * with the 

 angular. There are no sharp lines of demarcation be- 

 tween the occipital and temporal lobes. In the occipital 

 lobe of my Orang the transverse occipital fissure was 

 present, and received the parietal fissure. The calcarine 

 fissure was well marked, but was separated in the Orang 

 from the parieto-occipital fissure by the " deuxieme plis 

 de passage interne " of Gratiolet, the " untere innere 

 Scheitelbogen-Windung "of Bischoff. The cuneus of the 

 Orang is therefore somewhat different from that of man. In 

 man I have seen these two fissures separated as an ano- 

 maly. The calcarine passed into the hippocampal fissure, 

 so that in the Orang, as in monkeys generally, the gyrus 

 fornicatus was separated from the hippocampal gyrus, 

 whereas in man these convolutions are continuous. 

 This disposition has been noticed in the Hylobates, in 

 Ateles, and in one Chimpanzee, where the calcarine did not 

 reach the hippocampal. The first occipital gyrus is very 

 well developed, and as the late Professor Gratiolet 

 observed, is one of the most striking convolutions 



Fig. 4. 

 in the brain of the Orang. It rises so to the surface 

 that the internal perpendicular fissure or external part 

 of the parieto-occipital fissure is almost entirely bridged 

 over, the operculum so characteristic of the monkey 

 almost disappearing. It is continuous with the upper 

 parietal lobule arching around the parieto-occipital 

 fissure. This convolution comes to the surface in the 

 Hylobates and Ateles almost to the same extent as in 

 the Orang, but it is more developed in the latter than in 

 the Chimpanzee. It is called also the " premier plis de 

 passage externe," by Gratiolet, the " obere innere 



Scheitelbogen-Windung," by Bischoff, the " first an- 

 nectant gyrus," by Huxley, and "first bridging convolu- 

 tion," by Turner. The second occipital convolution 

 connects the occipital lobe with the angular gyrus. In 

 my Orang it was partly concealed by the first occipital. 

 It was not as superficial as in man, The third occipital 

 gyrus is continuous with that part of the temporal lobe 

 below the first temporal fissure. I noticed, also, in my 

 Orang the " quatrieme plis de passage " of Gratiolet. 

 On the mesial side of the occipital lobe in my Orang 

 was well seen the " deuxieme plis de passage interne " 

 of Gratiolet, the " untere innere Scheitelbogen-Windung " 

 of Bischoff, which separates the calcarine from the pari- 

 eto-occipital fissure ; and in both the Orang and Chim- 

 panzee, more especially on the left side, I had no diffi- 

 culty in recognizing the "■ premier plis de passage 

 interne " of Gratiolet, its convexity turning inwards, 

 while that of the first occipital gyrus, or the " premier 

 plis de passage externe," turns outward. These two 

 convolutions, the first occipital gyrus and the '■ premier 

 plis de passage interne," in my Orang were continuous. 

 They are regarded as one by Bischoff, forming his 

 " obere innere Scheitelbogen-Windung," but as two by 

 Gratiolet, constituting his " premier plis de passage ex- 

 terne et interne." 



The temporal lobe in the Orang is much less convo- 

 luted than in man, or even in the Chimpanzee. The first 

 temporal fissure and first temporal convolution are well 

 marked, but the second and third are badly defined 



Fig. 5. 



The fusiform and lingual lobes are separated by the in- 

 ferior occipito-temporal fissures, the collateral fissures of 

 Huxley. The Island of Red was perfectly covered in 

 both the Chimpanzee and the Orang by the operculum, 

 but was not convoluted in my Orang. The surface in 

 places was slightly roughened. I noticed, however, 

 three or four convolutions in the Chimpanzee. On mak- 

 ing a section of the left hemisphere of the Orang I no- 

 ticed that the corpus callosum was relatively smaller 

 than in man, but that the ventricle exhibited an anterior, 

 middle and posterior cornu, the corpus striatum, taenia 

 semicircularis, thalamus opticus and fornix were well 

 developed, the hippocampus major with corpus fimbria- 

 tum were perfectly evident, and the hippocampus minor 

 larger relatively than in man. I did not see a trace of 

 the emmenentia collateralis ; this is often, however, ab- 

 sent in man. 



The cerebellum in my Orang was relatively larger 

 than that of man, but smaller than that of either of the 

 Chimpanzees I have dissected, and was just covered and 

 no more by the posterior lobes of the cerebrum. This 

 relation is still retained in my Orang, though the brain 

 has been lying in alcohol for three months since it was 

 taken out of the chloride of zinc in which it was placed 

 until the pia mater could be removed. During th s period 

 it has been subject to the conditions, such as the want of 

 the support of the membranes, the effect of pressure, 

 etc., urged by Gratiolet, Huxley, Rolleston, Marshall, 

 etc., as sufficient to explain why after death the cerebel- 

 lum is uncovered by the cerebium in the Orang and 

 Chimpanzee, as held by Owen, Schroder van der Kolk 

 and Vrolik, and Bischoff. Every anatomist knows that 



