The brain of the mountain gorilla(Gorilla gorilla beringei)

PRIMATES, Vol. 4, No. 4, 1963

The Brain of the Mountain Gorilla

(Gorilla gorilla beringei)

II. Fissural Pattern"

HIROSHI HOSOKAWA and TOSHIRO KAMIYA

Department of Anatomy Faculty of Medicine, University of Tokyo

Tokyo

The fissural pattern of cerebral hemispheres of the mountain gorilla (Munidi and Emmy),21 of which the encephalometric data were reported in the previous paper (Hosokawa & Kamiya, '63), was examined macroscopically and compared with that of the lowland gorilla, chimpanzee, orang-utan, gibbon, as well as that of various kinds of monkey.

The external morphology of the gorilla brain has been described already by Thane (1876), Pansch (1876), Bischoff (1877, 78, 82), groca (1878), Chap- man (1892), Marchand (1893), Beddard (1899), Ingalls (1914), Bolk (1920), Le Gros Clark (1927), Tilney et al. (1928), Connolly (1950), etc., and the total number of their specimens amounted to more than thirty.3) Connolly's work especially was extensive and detailed, using 330 monkey brains representing over fifty species from lemurs to anthropoids. Some of the gorilla specimens reported by the preceding authors are illustrated in Figs. 1 & 2.

The materials of previous authors were mostly lowland gorilla brains, except one case described by Connolly. This was a three-year-old male named Okero, of which the brain is shown in Fig. 2-d, e. Our observations have revealed that there are no essential differences in the cerebral fissural configurations between the lowland and the mountain gorilla. So the following descriptions and discussion principally concern the gorilla brain in general.

1) To the memory of late Prof. emeritus Tsunetaro Fujita. 2) Munidi: adult male, body length 170.5cm, body weight 130kg. Emmy: adult female, body

length 139.0cm, body weight 68kg. Visceral organs of these mountain gorillas were studied anatomically by the same authors (Hosokawa & Kamiya, '61-62).

3) Number of brains: Thane, Pansch (1), Bischoff (1), Broca (1), Marchand (1), Chapman (1), Beddard, E. Smith (5), Ingalls (1), Bolk (2), Le Gros Clark (1), Tilney et al. (1), Connol- ly (13).

24 H. HOSOKAWA and T. KAMIYA

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Fig. 1. Gorilla brains reported by previous authors (1). a, b - -b ra in A of Bolk ('20). c, d - -Bra in B of Bolk.

e, f - -bra in of Le Gros Clark ('27).

The Brain of the Mountain Gorilla 25

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Fig. 2. Gorilla brains reported by previous authors (2). a brain of Tilney et al. ('28~. b, c brain B of Bolk d. e mountain gorilla brain of Connolly '50' . f- j--goril la brains of Connolly '50~.

'20).


1. Observa t ions

The fissural patterns of the two mountain gorilla brains (Munidi and Emmy) as well as of that of one young female lowland gorilla (Nissy) are shown in Figs. 3-8 and 19-29. Summarizing mainly the configurations in the four mountain gorilla hemispheres, we will outline them here.

Lateral surface L~busfrontalis (Fig. 3): The sulcus centralis or Sylvian fissure (S), 70-75 mm in length, runs straight back and upwards, making a sylvic angle of some 74 ° to the F-O (fronto-occipital) line. The anterior and ascending rami of this fissure are absent, while the well-developed s. frontoorbitalis (fo) marks the border line between the lateral and orbital surfaces of the hemisphere.

The s. centralis (c) or Rolandic furrow, 90-95 mm in length, shows a slightly wavy course and its upper end just incises the dorsal margin of the hemisphere. Although the centralis is independent from any other sulci in Emmy's brain, it shows slight anastomoses with the posterior ends of the precentralis medius (right, left) as well as of the precentralis inferior (left) in Munidi' s brain.

The s. precentralis is poorly developed in Munidi, while it is fairly well differentiated in Emmy. It usually consists of two segments, the precentralis superior (pcs) and inferior (pci). These two segments are of different origin, since the inferior one is derived from the ascending part of the arcuatus of monkey brains, while the superior one is apparently the newcomer in the higher monkeys. The precentralis of Munidi consists of three segments, which are situated rather obliquely. So the anterior border of the precentral gyrus is obscure.

The sulci frontales are poorly and irregularly developed. The posterior ends of the frontalis superior (fs) and inferior (fi) often join the precentralis superior and inferior respectively. Anterior to the frontalis inferior and very often continuous to this sulcus is the well-developed s. rectus (r), the forerunner of the s.frontomarginalis of human brain. It is noteworthy that the fissural pattern of this area of the gorilla brain shows the typical transitional form between monkey and man.

The ss. orbitales (o) (Figs. 4, 5) are so variantly arranged that it is difficult to determine the standard type of the fissural pattern of the orbital surface. The constant s. olfactorius, some 17mm in length, bounds the gyrus rectus, which is about 4mm in breadth. Lobus parietalis (Fig. 6): The s. postcentralis is divided into the postcentralis superior (pts) and inferior (pti) by the crossing with the anterior end of the s. intraparietalis (ip). Sometimes it even seems as if the intraparietalis forms the direct continuation of the postcentralis inferior, giving off the postcentralis superior as a side branch. This is a remnant of the monkey type, where the

intraparietalis and postcentralis inferior form a single groove. Thus the postcentralis superior is, like the precentralis superior, a newcomer in the higher

The Brain of the Mounta in Gorilla 2?

F i g . 3.

c pcs

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Frontal lobe of gorilla brains. M--Munidi (adult male mounta in gorilla). E--Emmy (adult female mounta in gorilla). N--Nis~y (young female lowland gorilla).

(Abbreviations are exp!ained on page 49.)


I r

//4/ ~/tb F

Fig . 4. Orbital sulci of Munidi (M), Emmy (E), and Nissy (N). Fig . 5. Orbital sulci of gorilla brains.

a, b Bolk, c--E. Smith, d- -Marchand, e--Broca, f~Chapman. (from Bolk '20)

The Brain of the Mounta in Gorilla 29

M

Fig. 6. Posterior part of cerebral hemisphere of Munidi, (M), Emmy, (E) and Nissy (N).

(Abbreviations are explained on page 49.)


primates. On the left hemisphere of Nissy (lowland gorilla) the postcentralis superior is separated from the inferior segment.

The gyrus poslcentralis, 12-17mm in breadth, is furnished with several accessory sulci, of which the lowest one is s. subcentralis posterior (scp). The lower end of the postcentralis inferior is bifurcated and its anterior and posterior extremities approach close to the s. centalis and s. lateralis respectively.

The s. intraparietalis arises from the postcentalis inferior and passes backwards, forming an upward convex curve of which the posterior end usually joins the well-developed s. lunatus (L).

The lobulus parietalis superior is rather small, provided with a fragmentary s. parietalis superior (ps). On the contrary the lobulus parietalis inferior is well- developed and the gyrus supramarginalis, as well as the g. angularis, can be identified. Lobus occipitalis : The occipital lobe is bounded anteriorly by the well-developed s. lunatus (L), 60-65mm in length, which represents the remnant of the simian fissure (Affenspalte). The upper end of this furrow incises the dorsal margin of the hemisphere. The upper end of the parietooccipitalis (po) sometimes joins the s. lunatus, while occasionally it is separated from the latter by an exposed gyrus, which is called the "first (or medial) annectant gyrus."

The lateral surface of the occipital lobe is marked by the s. calcarinus externus (ce) and the occipitalis inferior (oi), both of which show variant arrangement from one hemisphere to another. The occipital gyri are as a whole well-developed, showing strong and thick convolutions. So their configurations are quite different from that of the human occipital lobe. Lobus temporalis: The s. temporalis superior (ts) is in monkey brains often called parallel sulcus, since it runs straight and parallel with the Sylvian sulcus. This situation is left still considerably well in the gorilla brains, while its posterior extremity shows an upward bending and complicated branchings in the inferior parietal lobule.

The gyrus temporalis superior is narrow (6-9mm in breadth), while the g. temp. medius is somewhat broader (8-15mm in breadth). The s. temporalis inferior (ti) usually consists of several fragments, which are arranged close to the lower margin of the temporal lobe.

Medial surface (Fig. 7) The s. cinguli or callosomarginalis (cm) shows often fragmentation and

many bendings, separating the g. cinguli from the superior frontal gyrus. The posterior end of this sulcus turns upwards and incises the dorsal margin of the hemisphere. Just in front of the upper incision of the s. centralis is the s. precentralis medialis, which marks the anterior border of the lobulus paracentralis (anteroposterior length 25mm, height 20mm).

Beneath the splenium of the corpus callosum lies the s. rostralis (rs), which

is sometimes doubled by the s. rostralis inferior or accessorius (rsi). The s. subparietalis (sp) is situated obliquely marking the lower border of

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the precuneus (antero-posterior length 23-24 ram, height 20-22mm). The s. parietooccipitalis (po) arises independently of the s. calcarinus (cal)

and is always duplicated, forming a small area in between corresponding to the lobulus parieto-occipitalis (Retzius) or cuneolus anterior of the human brain. The separation between the parietooccipitalis and calcarinus is due to the exposure of Ecker's convolution (gyrus cunei of Ecker) which occurs in 2-4% of the human hemispheres.

The cuneus of Munidi measured 47mm (left) and 34mm (right) in length, 25mm (left) and 29mm (right) in height.

Peculiarly enough the anterior end of the s. calcarinus (cal) incises the s. hippocampi (h) in all four hemispheres of the mountain gorilla. Thus the gyrusfornicatus is clearly divided into the gyrus cinguli and g. parahippocampalis.

The posterior end of the calcarinus is bifurcated into two branches, which run closely along the dorsal border of the hemisphere.

In the depth of s. hippocampi is the gyrus dentatus, which lacks, however, the dentate appearance as seen in human brain.

Basal surface (Fig. 8) The s. rhinalis (rhin) is distinctly developed, separating the anterior end of

the gyrus parahippocampalis from the gyrus occipito-temporalis lateralis. The parahippocampal gyrus is some 10mm in breadth, while it is about

16mm at the uncus. On the medial side of the uncus there are neither distinct gyrus semilunaris nor g. ambiens.

In the posterior portion the s. collateralis (col) and s. occipitotemporalis (or) run parallel with the calcarine sulcus, bounding the gyrus occipitotemporalis medialis (lingualis), 6-8ram in breadth, and lateralis (fusiformis), 7-9ram in breadth, successively. Lateral to the s. oceipitotemporalis is the gyrus temporalis inferior.

The posterior end of the collateralis is sometimes (in Munidi) displaced transversely so as to form the s. occipitomarginalis basialis (ob).

2. Comparison o f the f issural pattern between goril la and man

When the fissural pattern of the gorilla brain is compared with that of the human brain, it is evident that, although there are some similarities in general appearance, the former shows several features which are quite different from the latter.

First of all the fissural pattern of the gorilla brain as a whole is considerably simpler than that of man. In other words the cerebral sulci run more straight, showing fewer bendings, branchings, and accessory sulci.

In the frontal region, such sulci as precentralis, frontales, and orbitales are apparently not so well-developed, while it is noteworthy that the s. rectus or

frontomarginalis is well-developed, implying the remnant of the simian type. Furthermore the anterior and ascending rami of the lateral sulcus are absent


Fig. 8. Basal surt~ce of cerebral hemisphere of Munidi (M), Emmy (E) and Nissy (N), P--chimpanzee.

(Abbreviations are explained on page 49.)


in the gorilla brain, probably indicating the poor development of the gyrus frontalis inferior as well as of the insula.

On the posterior half of the hemisphere, the postcentralis inferior continues upwards and backwards distinctly to the intraparietalis, while the postcentralis superior is also considerably well-developed.

The posterior end of the intraparietalis is in close association with the well-developed lunatus, the remnant of the peculiar simian fisssure (Affenspalte).

3. C o m p a r i s o n o f the f issural pattern a m o n g great apes

It is generally believed that the gorilla stands highest in the series of the anthropoid great apes. As far as the somatic structures are concerned, it is true that the gorilla shows features nearest to man in the animal kingdom. According to our encephalometric studies, however, it was revealed that the brain of the chimpanzee is nearest to that of man in its shape and indices.

How about the fissural pattern of the cerebral hemisphere? There have been published a considerable number of papers on the cerebral sulci of the chimpanzee and orang-utan, since they have been the popular stars of many zoological gardens all over the world (Mingazzini, 1928; Tilney et al. '28; Connolly, '50, etc.). In figures 9-12 some samples of our own specimens are shown. Comparing these figures with that of the gorilla brain, it is evident that there exist remarkable similarities in the fissural pattern among these three anthropoids, and it is quite difficult to draw clear-cut border lines between each two of them. At the same time, however, it can not be denied that the gorilla, chimpanzee, and orang-utah brains have some characteristic '"nuances" of their own, showing some differences of the complexity of the fissural configurations.

Especially in the frontal region the fissural pattern is most simple in the orang-utah brain, because the ss. precentrales and frontales as well as accessory sulci are few in number, short in length and distant from one another. In the posterior part of the hemisphere, too, the inferiority of the orang-utan brain is evident from, for instance, the incompleteness of the s. postcentralis. Com- paring the gorilla and chimpanzee brains, it is noteworthy that the sulci in general of the latter are more wavy and approach more closely to one another, giving the appearance of more complex configurations.

So, it may be concluded that, so far as the fissural configurations of the cerebral hemispheres are concerned, the chimpanzee brain shows the highest complexity, while the gorilla and orang-utan brains follow successively.

Thus the conclusion coincides with that of our encephalometric data in ranking the chimpanzee highest in the anthropoids. This ranking was also suggested by Connolly (1950).

The gibbon, which apparently stands lower than the other anthropoids, shows a considerably simpler fissural pattern especially in the frontal region


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Fig. 9. Fissural pattern of chimpanzee brains (1). Frontal lobe.


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Fig. 10. Fissural pattern of chimpanzee brains (2). Posterior part of cerebral hemisphere.


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Fig. 11, Fissural pattern of orang-utan brains (1). Frontal lobe.


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Fig. 12. Fissural pattern of orang-utan brains (2). Posterior part of cerebral hemisphere.


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Fissural pattern of gibbon brains (1). Frontal lobe.


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Fig. 14. Fissural pattern of gibbon brains (2). Posterior part of cerebral hemisphere.


(Figs. 13, 14). While the rectus sulcus is markedly well developed, the precentrales and frontales are merely indicated; that is to say, the fissural pattern of the gibbon brain represents, so to speak, the intermediate form between the monkeys and anthropoids.

4. F i s sura l pattern o f the m o n k e y s

For the purpose of understanding the fissural pattern of the brain of the gorilla and other anthropoids, the brains of monkeys were collected and studied. Since it is difficult to obtain brains ofplatyrrhine monkeys, the present observa- tion was limited to the catarrhine monkeys, Cercopithecidae. Some of the papers on the monkey brains were also referred to (Pansch, 1868; Ziehen, 1896; Zu- ckerkandl, 1902, '03, '05; Kohlbrugge, '03; Geist, '30; Connolly, '50. etc.).

As a matter of fact, the anthropoids are more intimately related to the catarrhine monkeys than to the platyrrhine. Figs. 15-16 show some samples of the monkey brains.

First of all, the straight course of the s. centralis is noteworthy in the monkey brains. In the frontal region the rectus (r) and arcuatus (a) sulci are markedly developed in all brains examined, implying that these two sulci characterize the monkey brains. In other words, the rectus and arcuatus form the fun- damental pattern of the frontal region, modified by the indications of the precentralis and frontales.

The posterior part of the hemisphere of the monkey brain is characterized by the "V"-shaped arrangement of the intraparietalis and lunatus (Fig. 16). This "V" is inverted and encloses the posterior ends of the lateralis and temporalis superior (parallel sulcus) which are in close approximation to each other. The tip of this "V" is very often connected with the dorsal end of the parietooccipitalis.

As the differentiation advances the intraparietalis begins to show an upward convex curve, modifying the "V" into a somewhat quadrangular contour. This bending foretells the appearance of the postcentralis inferior in the anthropoid brains.

The external surface of the occipital lobe is smooth in primitive monkeys, while calcarinus externus appears and develops in higher forms.

5. D e v e l o p m e n t o f the f i ssural pat tern o f the cerebral hemi - sphere in the pr imate ser ies

Many authors have endeavored to clarify the evolutional development of the cerebral fissural pattern in the primates (Cuningham, 1892; Ktikenthal & Ziehen, 1895; E. Smith, 1902, '04; Shellshear, '27; Tilney et al., '28; Con-

nolly, '50; A. Kappers, Huber & Crosby, '60. etc.). From the foregoing observations and descriptions of the present authors


it was revealed that there is a definite tendency of development of the fissural pattern in the catarrhine primates. The principles of the development are shown somewhat diagrammatically in Figs. 17-18.

In the frontal region the monkey brain is, so to speak, of the rectus-arcuatus type, which develops and differentiates into the precentralis-frontales type in the anthropoids and man. In the posterior part of the hemisphere, the monkey brains are of the characteristic intraparietalis-lunatus type, while it is modified into the postcentralis-intraparietalis type in the anthropoids and man.

In the following are more detailed items which may represent the criteria for judging the degree of evolution of the cerebral fissural pattern in the catarrhine primate series.

Monkeys Anthropoids Man 1) Complication of the whole fissural 4- < @ <

pattern 2) Curving and bending of s. centralis 4- < + < @ 3) Decline of s. rectus @ > 4- > 4- 4) Decline of s. arcuatus @ > 4- > 4- 5) Development of s. precentr, inferior 4- < 4- < @ 6) Development of s. precentr, superior 4- < 4- < 4t- 7) Development of ss. frontales 4- < 4- < q+ 8) Development of ss. orbitales 4- < 4- < @ 9) Independence of s. lat. and 4- < 4- < @

s. temp. sup. 10) Independence of s. postcentr, inf. 4- < 4- < @

and intraparaiet. 11) Appearance and development of 4- < 4- < @

s. postcentr, sup. 12) Decline of s. lunatus (simian sulcus) q4f > -H- > 4- 13) Independence of s. intrapariet., -- < 4- < @

s. lunatus and s. parietooccipit. 14) Development of s. pariet, sup. 4- < 4- < @

(Development of lobulus pariet. sup.)

15) Development of s. calcarinus ext. 4- < 4- < @ (Development of ss. occipitales)


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Fig. 15. Fissural pattern of monkey brains (1). Frontal lobe. a--Macaca philippinensis, b - - M . nemestrina, c - - M . irus. d - - M . mulatta, e - - M. fuscata, ~ M . cyclopsis, g--Semnopithecus, h--baboon.


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Fig. 16. Fissural pattern of monkey brains (2). Posterior part of cerebral hemisphere.

Species are the same-as are in*Fig. 15.


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Fig. 17. Development of fissural pattern in primate series (1). Frontal lobe. a--Macaca, b--Comopithecus, c--gibbon, d--orang-utan, e--gorilla, f - - chimpanzee, g--man.


/

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Fig. 18. Development of fissural pattern in primate series (2). Posterior part of cerebral hemisphere, a--Macaca nemestrina, irus, etc. b - - M . mulatta, c - -M. fuscata, d - - M . cyclopsis, e--baboon, f~gibbon, g--orang-utan, h - - chimpanzee, i - - gorilla.


Summary

The fissural pattern of two brains of the mountain gorilla (Gorilla gorilla beringei) was studied macroscopically and compared with that of man, lowland gorilla (Gorilla gorilla gorilla), chimpanzee, orang-utan, gibbon and monkeys. Our main conclusions are as follows.

1. No definite difference was noticed in the arrangements of cerebral sulci between the two subspecies of the gorilla (mountain and lowland gorilla).

2. Although gorilla, chimpanzee and orang-utan show remarkable similarities in the fissuration of the cerebral hemisphere and it is difficult to draw clear-cut border lines between each two of them: there is the general tendency that the chimpanzee brain stands highest in the complexity of the fissural configurations, while the orang-utan is situated below the other two.

The gibbon shows apparently a by far lower differentiation of the cerebral sucli compared with other anthropoids.

3. The fissural pattern of the gorilla as well as of the other great apes is considerably simpler than that of man, representing, so to speak, the intermediate form between man and monkeys.

4. Comparing the fissural pattern of the anthropoids and of man with that of monekys (Cercopithecidae), the serial development in the cerebral fissuration was traced from the monkey through the anthropoids to man. The monkey brain is, so to speak, represented by the combination of the rectus-arcuatus type and intraparietalis-lunatus type, while the brains of anthropoids and man are the combination of the precentralis-frontales type and postcentralis-intraparietalis type.

5. Items or criteria for indicating the evolutional development of the cerebral fissuration in the catarrhine primate series were proposed.

Acknowledgments

The authors are cordially grateful to the staff of the Japan Monkey Centre for their kindness in lending these precious gorilla specimens. We are also in- debted to Prof. Kusama of the Brain Research Institute of Tokyo University, Dr. Kobara of Nogeyama Zoo of Yokohama City, and to the Laboratory of Physical Anthropology of Kyoto University for their willing kindness in lending or collecting monkey brains.

REFERENCES

1) Arifins Kappers, C.U., G.C. Huber & E.C. Crosby, 1960. The comparative anatomy of the nervous system of vertebrates including man. Vol. 3, Hafner, New York.

2) Beddard, F.E., 1899. A contribution to our knowledge of the cerebral convolutions of the gorilla. Proc. Zool. Soc. London. 65-76.

3) v. Bischoff, Th., 1877. Ueber das Gehirn eines Gorilla. Sitz. ber. d. Math-physik. Klasse d. k. bayer Akad. Mtinchen. 1877:96. (Cited from Keith, 1895 & Beddard, 1899)

48

4)

5)

H. HOSOKAWA and T. KAMIYA

- - , 1878. Das Gorillagehirn und die untere oder dritte Stirnwindung. Morph. Jahrb. 4. Suppl. 59473.

- - , 1882. Die dritte oder untere Stirnwindung und die innere obere Scheitelbogen- windung des Gorilla. Ibid. 7 : 312-322.

6) Bolk, L., 1910. Beitrfige zur Affenanatomie. VII . Das Gehirn von Gorilla. Z. f. Morph. u. Anthropol. 12 : 141-242.

7) Broca, P., 1878. l~tude sur le cerveau du gorille. Revue d'Anthropol. 7 : 1-46. 8) Chapman, H.C., 1892. Observations upon the brain of the gorilla. Proc. Acad. Nat.

Sci. Philadelphia. 1892 : 203. (Cited from Beddard, 1899) 9) Clark, W.E, Le Gros, 1927. Description of the cerebral hemispheres of a gorilla (John

Daniels II) . J. Anat. 61 : 467-475. 10) Connolly, C.J., 1950. External morphology of the primate brain. Charles C. Thomas,

Springfield, Ill.

11) Cunningham, D.J., 1892. Contribution to the surface anatomy of the cerebral hemispheres. Roy. Irish Acad., Cunningham Memoirs, No. 7.

12) Elliot Smith, G., 1902. On the homologies of the cerebral sulci. J. Anat. 36 : 309-319. 13) - - - - , 1904. The morphology of the occipital region of the cerebral hemisphere in

man and the apes. Anat. Anz. 24 : 436-451. 14) Geist, F.D. 1930. The brain of the rhesus monkey. J. Comp. Neur. 50 : 333-375. 15) Hosokawa, H. & T. Kamiya, 1961-62. Anatomical sketches of visceral organs of the

mountain gorilla. Primates, 3-(1): 1-28. 16) , 1963. The brain of the mountain gorilla. I. Encephalometry. Primates, 4-

(3) : 67-95.

17) Ingalls, N.W., 1914. The parietal region of the primate brain. J. Comp. Neur. 24 : 291- 341.

18) Keith, A., 1895. The growth of the brain in men and monkeys, with a short criticism of the usual method of stating brain-ratios. J. Anat. 29 : 282-303.

19) Kohlbrugge, J.H.F., 1903. Die Variationen an den Grosshirnfurchen der Affen mit be- sonderer Beriicksichtigung der Affenspalte. Z. f . Morph. u. Anthropol. 6:191-250.

20) Kiikenthal, W. & Th. Ziehen, 1895. Untersuchungen fiber die Grosshirnfurchen der Primaten. Jena. Z. f. Naturw. 29:1-122.

21) Marchand, F. 1893. Die Morphologie des Stirnlappens und der Insel der Anthropo- morphen. Arb. a. d. path. Inst. zu Marburg. Bd. 2. (cited from Connolly, '50)

22) Mingazzini, G., 1928. Beitrag zur Morphologie der ~iusseren Grosshirnhemisphiirenober- fliiche bei den Anthropoiden (Schimpanse und Orang). Arch. Psychiat. u. Nervenkr. 85:1-219.

23) Pansch, A., 1868. Ueber die typische Anordnung der Furchen und Windungen auf den Grosshirnhemisph~iren des Menschen und der Affen. Arch. f. Anthropol. 3:227-257.

24) ~ , 1876. Ueber die Furchen und Windungen am Gehirn eines Gorilla. Abhandl. Geb. Nat. Hamb. 1876. (Cited from Beddard, 1899)

25) Shellshear, J.L., 1927. The evolution of the parallel sulcus. J. Anat. 61:267-278. 26) Thane, G. D., 1876. The brain of the gorilla. Nature. 15:142-144.

27) Tilney, F., H.A. Riley, & H.F. Osborn, 1928. The brain from ape to man. 2 vols. Paul B. Hoeber, New York.

28) Ziehen, Th., 1896. Ueber die Grosshirnfurchung der Halbaffen und die Bedeutung eini- ger Furchen des menschlichen Gehirns. Arch. f. Psychiat. u. Nervenkr. 28:898-930.

29) Zuckerkandl, E., 1902. Zur MorphologiedesAffengehirnes. Z.f. Morph. u. Anthropol. 4:463-499.

30) - - , 1903. Zur Morphologie desAffengehirnes. Zweiter Beitrag. Ibid. 6:285-321. 31) - - , 1905. Zur Morphologie des Affengehirnes. Vierter Beitrag. Ibid. 8:100-122.

T h e Bra in o f t he M o u n t a i n Gor i l l a 49

Abbreviat ions

a sulcus arcuatus

c s. centralis

cal s. calcarinus

cc s. corporis callosi

ce s. calcarinus externus

c m s. callosomarginalis

col s. collateralis

fi s. frontalis inferior

f m s. frontalis medius

fo s. frontoorbitalis

fs s. frontalis superior

h s. hippocampi

io incisura opercularis

ip s. intraparietalis

L s. lunatus

o ss. orbitales

ob s. occipitomarginalis

basialis

oi s. occipitalis inferior

ot s. occipitotemporalis

pci s. precentralis inferior

p c m s. precentralis medius

pcs s. precentralis superior

po s. parietooccipitalis

ps s. parietalis superior

pt i s. postcentralis inferior

pts s. postcentralis superior

r s. rectus

r h n s. rhinalis

rs s. rostralis

rsi s. rostralis inferior

S s. lateralis (fissura sylvii)

sca s. subcentralis anterior

scp s. subcentralis posterior

sp s. subparietalis

ti s. temporalis inferior

ts s. temporalis superior


plate I. Figs. 19-23. Brain of Munidi (adult male mountain gorilla).


plate II. F~gs. 24-29. Brain of Emmy (adult fema!e mountain gorilla).

Documents

The brain of the mountain gorilla(Gorilla gorilla beringei)