TRANSACTIONS OF SECTION D. 639 



described by the author in Volume V. of the National Antarctic Expedition 

 Natural History. The object of this paper was to draw attention to the remark- 

 ably early stage of foetal life at which all these adaptive modifications become 

 fully established, and the possible bearing which such facts may have upon the 

 question of the inheritance of acquired characters. 



3. The Temporal Bone in Primates. By Professor R. J. Anderson, M.D. 



The temporal bone is usually regarded as a bone of the cranium, chiefly 

 because of the relations of the petro-mastoid portion. The squamosal has so 

 much to do with the face bones that it might be considered as occupying an 

 intermediate positon. The zygoma brings the temporal squamosal into relation 

 with the jugal, and sometimes the maxilla. The squamosal may reach the jugal 

 apart from the zygomatic connection. The direct relationship of the mandible 

 with the temporal in mammals obviously emphasises the connection of the. 

 squamosal with the face. In primates the size of the squamosal varies. It is 

 much reduced in some rodents. It looks like an arch from beneath which the 

 petro-mastoid appears behind and the tympanic in front. The squamosal has 

 a connection with the brain-case in man that looks more evident on the outside 

 of the skull than on the inside. The parietal runs down internally, separating 

 much of the temporal squamosal from the cranial cavity. In Equidas the facial 

 relationship is most pronounced. The tympanic may have independent 

 mechanical functions also (as in some mammals). The squamosal may preserve 

 its identity for a long time, or during life (as in a gorilla in the Museum 

 d'Histoire Naturelle de Paris referred to by Le Double), and in the chimpanzee 

 the persistence of the suture is not uncommon. Occasionally the zygomatic and 

 squamose parts are separate. Of this condition, which is due to developmental 

 causes, Meckel and Griiber record instances. Le Double found the squamosal 

 divided. I believe I have met this once in man, and also in the chimpanzee. 

 In the latter the upper triangular part looks like a Wormian bone. The effect 

 of the facial growth on the nutrition of the temporal may lead to two sources of 

 supply being emphasised. The cranial portion may then go with the cranial 

 supply. Three centres of ossification are present in man in the case of the 

 squamosal, one for the zygoma, one for the scale, and a third for the ear part. 

 Four centres may be present. This condition seems rare in primates, and it ia 

 difficult to decide upon the normal number. Ossific foci are apt to vary with the 

 nutrition, and that the ossific deposits are very sensitive to such changes an 

 examination of the skulls of primates bred in captivity amply proves. 



Le Double gives a second suture in squamosal of Ateles. The anterior range 

 of the temporal depends on the development of the parietal and the sphenoid. 

 A postal process is often found in primate skulls — in one in seven skulls in 

 Australian aborigines. In Papuans the abnormality is rarer, and it is still rarer 

 in white and yellow races. It is the usual thing in gorillas, less common in 

 chimpanzees, much less so in orangs, and less so in gibbons. This connection 

 seems to show a tendency in some types to emphasise the relationship of the 

 temporal with the facial as in ungulates and rodents. Le Double, following 

 Calori, Broca, Griiber, and Virchow, regards the process as theromorph. 

 Anoutchine (Stieda), Rathke, and recently Schwalbe, take a different view. 

 The possibility of the advance being due to the formation of Wormian bones and 

 their subsequent union to the temporal is certain. The tympanic has three 

 ossific foci also. The centre for the styloid process is variable. Owen mentions 

 that the styloform process or angle in gorilla contrasts with the absence of 

 this in chimpanzee. 



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