rrsHES. 51 



remains of the notochord) ; on each side, the exoccipital (10) ; and 

 the supraoccipital above (8), which is raised into a crest. The 

 formation of the posterior part of the skull is completed by the 

 mastoids (12) and parietals (7). 



On the lower surface of the skull (fig. 38) are seen the basi- 



Lower view of skull of Perch. 



sphenoid (6), the vomer (16), which, like the palatines, is beset 

 with teeth, the alisphenoids (11), and orbit o sphenoids (14). 



In addition to these bones we have to notice those of the 

 upper surface of the skull (fig. 37), viz. the frontals (1), the 

 prefrontals (2), the postfroyitals (4), and the turbinals (20), all 

 paired bones. 



Attached to the skull are the hyo-branchial apparatus and the 

 scapular arch (figs. 39, 40). 



