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that the bones are divided into a lower portion which is triangular, 

 and an upper which is lozenge-shaped, the two being connected only 

 by a narrow neck. In the Chimpanzee the sides of the bones are 

 nearly parallel; they are no Avider at the lower than at the upper por- 

 tion, and are relatively very narrow. In neither the Gorilla nor the 

 Chimpanzee are these bones arched above the level of the face, though 

 in the former there is a slight ridge on the median line. The nasal 

 bones, as has been observed by Owen, are, as regards their shape, 

 more nearly human in the Gorilla than in the Chimpanzee. 



2. The orbits.- — In the Chimpanzee the orbits are nearly circular, 

 while in the Gorilla they are somewhat quadrangular, in which respect 

 these are more human. But in the proportion in which the dilFerent 

 bones enter into the formation of them, the resemblance to man is the 

 most striking in the Chimpanzee. In the lower Quadrumana, the 

 lower and outer walls of the orbits are mostly formed by the extension 

 of the outer and inner orbital edges of the frontal bones downwards, 

 so that the os planum of the ethmoid becomes quite narrow, and is 

 found near the floor of the orbit, and even forms a part of it, and 

 the great wing of the sphenoid is much lessened in size, and is confined 

 to the hindmost part of the orbital cavity. In these respects the 

 Gorilla most strongly resembles the other Quadrumana, and the Chim- 

 panzee makes the nearest approach to man. The Gorilla agrees 

 with other Mammalia in having the sphenoidal fissure round, and 

 the Chimpanzee with man in having it triangular, though in a less 

 degree, and its apex directed upwards and outwards. 



3. Intermaxillaries. — In man these bones cease to be distinct at so 

 early an embryonic period that their existence as separate pieces can- 

 not be easily demonstrated, and has in fact rarely been observed. In 

 the lower Quadrumana, as well as in Mammalia, generally the inter- 

 maxillaries remain distinct through life. In the cranium of the Gorilla 

 here described they are still entirely separate. Duvernoy found them 

 so in a skull in which the milk teeth were complete, and we have 

 found them still ununited with the maxillaries even in a nearly adult 

 specimen belonging to the Boston Society of Natural History. In a 

 young Chimpanzee, with only the middle incisors protruded, the 

 intermaxillary sutures are almost entirely closed, only traces of them 

 being visible on the borders of the nostrils and in the hard palate ; and 

 when the first dentition is ended, as appears from four crania in my col- 

 lection, their consolidation is completed. In the Gorilla the intermax- 

 illaries are prolonged much farther backwards than in the Chimpanzee, 

 so that the suture between them and the palatine process of the maxil- 

 laries, instead of being directed transversely to the incisive foramen, as 

 in man and the Chimpanzee, is bent strongly backwards, as in the lower 



