14 ANIMAL MECHANICS 



a peculiar manner; the lower, or temporal, bone 

 laps over the superior, or parietal, bone. This, 

 too, has been misunderstood : that is to say, the 

 plan of the building of the bones of the head has 

 not been considered ; and this joining, called the 

 squamous 1 suture, which is a species of scarfing, 

 has been supposed a mere consequence of the 

 pressure of the muscle which moves the jaw. 



Dr. Monro says, " The manner how I imagine 

 this sort of suture is formed at these places, is, 

 that by the action of the strong temporal muscles 

 on one side, and by the pressure of the brain on 

 the other, the bones are made so thin that they 

 have not large enough surfaces opposed to each 

 other to stop the extension of their fibres in 

 length, and thus to cause the common serrated 

 appearance of sutures; but the narrow edge of 

 the one bone slides over the other." 



The very name of the bones might suggest a 

 better explanation. The ossa parietalia 2 are the 

 two large bones in a regular square, serving as 

 walls to the interior or room of the head, where 

 the brain is lodged. See A in the foregoing 

 figure. 



Did the reader ever notice how the walls of a 

 house are assisted when thin and overburdened 

 with a roof ? 



1 From squama, the Latin for a scale, the thin edges lying over 

 each other like the scales of a fish. 



2 From the Latin word paries, a wall. 



