SKELETON OF CYCLOSTOMES. 



are three in the Sea-lamprey, of which the middle one is 

 joined to the palate by an intermediate smaller one ; the fore- 



A c 



Fig. 30 . — Upper (A) aud side (B) views, and vertical section (C) of the skull of 



Petromyzon niarinus. 

 a, Notochord ; h, Basis cranii ; c, Inferior, and d, Lateral process of basis ; e, 

 Auditory capsule ; /, Siibocular arch ; g, Stylohyal process ; h, Olfactory 

 capsule ; i, Ethmo-vomerine plate ; k, Palato-pterygoid portion of subocular 

 arch ; l-n, Accessory labial or rostral cartilages ; with o, appendage ; j), 

 lingual cartilage ; q, neural arches ; r, Branchial skeleton ; s, Blind termiua. 

 tion of the nasal duct between the notochord and oesophagus. 



most is ring-like, tooth-bearing, emitting on each side a styh- 

 form process. The lingual cartilage is large in all Cyclostomes, 



F 



