140 THE SKULL. [chap. 



The lachrymal foramen is never situated externally, to the 

 orbit, although, in the lower forms, it may be close upon 

 the margin. 



As in Man the postorbital process of the frontal meets 

 the orbital process of the malar so as completely to encircle 

 the outer side of the orbit ; and an extension backwards and 

 inwards of these bones joining the alisphenoid divides the 

 orbit from the temporal fossa. 



The nasal bones vary much in length and breadth, but 

 they present the peculiarity throughout the order of a great 

 tendency to ankylose together in the middle line, even at a 

 comparatively early age. 



In all the smaller and middle-sized Monkeys the general 

 surface of the calvaria is oval and smooth, but in the larger 

 Baboons and Orangs there are well-marked supraorbital, 

 sagittal, and occipital ridges. These attain their greatest 

 development in the adult male Gorilla, where they com- 

 pletely mask the original form of the cranium. Their size, 

 in this sex, appears to increase with age; while in the oldest 

 females, on the other hand, they are but slightly apparent. 



The paroccipital process is always rudimentary, as in 

 Man. 



The squamosal in the higher forms is developed much as in 

 Man; but in the lower forms it is more reduced, and takes a 

 smaller share in the formation of the side wall of the cranium. 

 It generally comes in contact, at its upper anterior angle, 

 with the frontal, but not in the Orang or in the Cebidtr., in 

 which animals the union of the parietal and the alisphenoid 

 separates the frontal from the squamosal, as is usually the 

 case with Man. The glenoid surface is natter than in Man, 

 and there is a well-marked postglenoid process. 



The zygoma is usually narrow, horizontal, and slightly 

 arched outwards. 



