xm 



PHYLUM CHOBDATA 



295 



an internal or ventral surface, an anterior or pre-axial border 

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

 border which terminates in the last digit. The eyes are small 



^^ 





K 





4 



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. d. 1, hr. cl. 3) leading into the pharynx, 

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



T 2 



