THE PINEAL EYES OF CYCLOSTOMES 199 



the flesh of fishes, but instead of clinging on to the surface of the body, 

 they actually bore their way into the flesh. 



The description of the pineal system of the extinct Ostracoderms, 

 which have been shown by Stensio and Kiaer to be very closely related to 

 the living representatives of the Cyclostomata, will be referred to in 

 Chapter 23, on the Geological Evidence of Median Eyes in Vertebrates and 

 Invertebrates. 



