34 



CYCLOSTOMATA 



trabeculae extends a median plate below the pituitary canal. The 

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



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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 



