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by a feeble tuberosity below the jugular process in the Gorilla, in which there are no post- 

 condyloid holes. The sutures between the exoccipitals and mastoids remain, but the rest of 

 the lambdoidal suture is obliterated in the Gorilla : the extent of the exoccipitals outside the 

 condyles is less than in Man. The superoccipital is a much broader plate than in Man, and 

 is flat or slightly concave externally, with all trace of the superior angle lost in the anchylosis 

 consequent on the development of the great lambdoidal ridge : it shows nothing answering to 

 the crucial ridge or spine of the human convex occiput. The basisphenoid, besides its non- 

 confluence with the basioccipital, has a larger extent uncovered by the vomer and by the 

 bases of the anchylosed alisphenoids and pterygoids : it is excavated by large sinuses extend- 

 ing into both the alisphenoids and pterygoids : the sinuses are confined to the basisphenoid 

 and presphenoid in Man. The broader pterygoids in the Gorilla anchylose with, and as 

 it were, embrace a greater part of the base of the alisphenoid : the foramen ovale is more re- 

 mote from the foramen caroticum, and is pushed by the broad ectopterygoid further back 

 from the pterygomaxillary fissure ; the extent of the basis cranii between the carotid foramen 

 and sphenomaxillary fissure being twice that in Man. The styliform process is less developed, 

 and the inner border of the glenoid cavity of the squamosal abuts against its whole length, or 

 even extends below or beyond it. Outside the pterygoid the alisphenoid becomes narrower, 

 and is continued more directly upwards into the temporal fossa than in Man : the ectoptery- 

 goid ridge is less developed, and the fossa on the outer side of the ectopterygoid is not 

 present, or is very feebly developed. The alisphenoid contracts instead of expanding as it 

 rises, terminates before it gains half the height of the orbit, and is excluded from junction 

 with the parietal by the meeting of the squamosal with the frontal : the expanded spine of 

 the parietal vertebra is thus entirely separated from its neurapophyses hi the Gorilla. In the 

 Australian the alisphenoid ascends higher than the malar, but not so far as in the European. 

 Besides the relatively smaller size of the parietal bones, the early obliteration of the sagittal 

 suture, and the development of the crista upon it in the Gorilla, the lower border of the 

 parietal is straighter than in Man and more equally divided between the squamosal and the 

 mastoid. The orbitosphenoids coalesce nearer their origin with the orbital plates of the ali- 

 sphenoid, obliterating the fissure which in Man is continued outwards from the 'foramen 

 lacerum anterius ' ; so that this foramen is better defined and has a subquadrate form in the 

 Gorilla ; and there are no ridges, called ' lesser alae,' defining the fossa of the anterior lobe 

 from that of the middle lobe as in Man. The suture between the orbitosphenoids and the 

 frontals is quite obliterated in the Gorilla. A short triangular plate divides the optic hole 

 from the foramen lacerum anterius on each side, which plates answer to rudiments of the 

 ' alse minores ' and to the bases of the anterior clinoid processes, but those processes are not 

 extended backwards as in Man. The foramen rotundum is closer to the foramen lacerum 

 anterius than in Man, and the stvliform foramen is closer to the foramen ovale. 



The mastoid bone is relatively larger, but developes a smaller and more hemispheric mastoid 

 process. Traces of the suture between the mastoid and squamosal continue longer in the 

 Gorilla than in Man. The upper part of the mastoid extends outwards into a strong angular 

 ridge, and its under part extends from the process inwards as a horizontal plate to join the 

 exoccipital, which plate is of greater extent than in Man, and is not grooved by the digastric 

 muscle ; thus the space between the occipital foramen and the external auditory foramen is 



