358 SCIENCE PROGRESS. 



Fraipont, to the size of the facial muscles. Cams, 1 on the 

 other hand, thought they were most strongly developed in 

 animals of keen sight. 



Much has been made of the frontal sinuses that inflate 

 the supra-orbital ridges, and are very large in the fossil 

 skulls. Huxley 2 cited evidence showing them to be corre- 

 lated with the respiratory apparatus. Others have thought 

 them correlated with the sense of smell. The frontal 

 sinuses are, however, in nowise different from those of the 

 maxillary, sphenoid, ethmoid and mastoid bones, which are 

 merely economical methods of gaining an increase of bulk 

 and surface with no increase of weight. 



The supra- orbital ridges terminate laterally in the 

 external angular processes, which, in the fossil skulls, are 

 extremely prominent. This process in the Bengawan 

 skull measures 18 m.m.; in the Neanderthal, 24 m.m.; in 

 Spy cranium No. 1, 16 m.m.; in Spy cranium No. 2, 14 

 m.m.; in Cynocephalic Australian skulls, from 12 to 20 

 m.m.; in the modern European, from S to 14 m.m.; in the 

 gorilla, about 40 m.m.; in the chimpanzee, frequently 30 

 m.m.; in the orang, about 2,^ m.m.; and in the Siamang, 

 about 22 m.m. The malar part of the temporal muscle 

 takes its origin from this process, so that its prominence in 

 human fossil skulls indicates for us the high degree to 

 which the malar part of the temporal muscle was developed 

 in fossil man — a development indicative of a heavy burden 

 of work upon the molar teeth. 



A prominent external angular process is also a simian 

 characteristic, and probably also a feature of the ancestral 

 primate stock. 



The temporal ridges on the human fossil skulls indicate 

 for us, by their situation on the parietal bone, and also by 

 their prominence, the degree to which the temporal muscles 

 were developed. The temporal ridges, bounding the tem- 

 poral area of the parietal, are decipherable with difficulty in 

 the Bengawan skull ; they are easily made out, but not 



1 Quoted by Fraipont. 



2 Evidence as to Alan's Place in Nature. 



