174 HUMAN EMBRYOLOGY AND MORPHOLOGY. 



bone before the growing muscles. The ridges may meet, as in 

 apes, along the sagittal and lambdoidal sutures and form crests, 

 like that on a fireman's helmet. In man the temporal ridges 

 and superior curved lines of the occipital bone also ascend with 

 the eruption of the permanent teeth, but only to a slight extent. 

 Man retains in the adult the condition seen in young apes. 



