384 



TRANSACTIONS OF THE AMERICAN PHILOSOPHICAL SOCIETY 



suspensoria of the mandible, together with the necessity for protecting the brain and sup- 

 porting the eyes and their associated muscles, have doubtless all contributed to the moulding 

 of the entire skull roof (Fig. 2635), which appears to be stiffened in accordance with the 

 truss principle so well known to civil engineers. As seen from above, the frontal plate bears a 



Opsanus tau 



Fig. 263. Opsanus. A. Side view. B. Top view. 



conspicuous T, of which the stem is formed by the sagittal crest of the supraoccipital, con- 

 tinued forward in the fused opposite frontals, while the cross-bar is formed by a stiff trans- 

 verse crest borne by the frontals. In front of the cross-bar, which is slightl)^ convex, the 

 raised postorbital rims afford further stiffening of the broad cranial table. From the outer 



