XIII 



PHYLUM CHORDATA 



295 



ail intorual or ventral surfiice, an anterior or ^rrc-axial border 

 which terminates in the first digit and a posterior or post-axial 



The eyes are small 



border which terminates in the last di^it 



■\3 



\>J 



p 



• H 

 ♦J 



u 



V 



o 



Id 



■H 

 ti 



s 



and have no eyelids, there is no tympanic membrane, and the 

 mouth is wide and bordered by thick lips. On each side of the 

 neck are two gill-slits (hr. cl. 1, hr. cl. 2) leading into the pharynx, 

 the first between the first and second branchial arches, the other 



T 2 



