34 



CYCLOSTOMATA 



trabeculae extends a median plate below the pituitary canal. The 

 lateral plate, pierced by a wide fenestra, forms a subocular arch, 



" = = _ = 



CT) C Sp.-O , 



S S 5 _ ^'n 



I 1 >.--' ";. I | 



a E s^* 



" 



w i .. , 



6 *" S'o'S " 5" 

 .2.= S"S j=_2 



g l.' tCd c - S" *o 

 5- -^ ^ ? c -"^ "t- 



and is continuous in front with two large bars which fuse to support 

 a powerful median ' ethmoid ' epidermal tooth. Cartilages support 

 the three pairs of cirrhi, and the edge of the mouth. 



The branchial skeleton is represented apparently by two or 



