233 



bels. Mouth, without lips. Nasal duct with 

 cartilaginous rings penetrating the palate. Median 

 tooth on the palate, and two comb-like series of 

 teeth on the tongue. Branchial apertures at a 

 great distance from the head. The inner branchial 

 ducts lead into the oesophagus. A series of mu- 

 cous sacs along each side of the abdomen. Intes- 

 tine without spiral valve. Eggs large with a horny 

 case provided, with threads for an adhension. 



" Inhabitants of the seas of the temperate regions 

 of both hemispheres ; burrow into other fishes, and 

 feed on their flesh." (Gunther.) 



Bdellostoma Cirrhatum (Bloch., Schneid., p. 582,) was found 

 by Forster in New Zealand. 



Sub-Class VI. LEPTOCAKDII. 



" Skeleton membrane, cartilaginous and notoch- 

 ordal, ribless, no brain. Pulsating sinues in place 

 of heart. Elood colourless. Respiratory cavity 

 confluent with the abdominal cavity; branchial 

 clefts in great number, the water being expelled by 

 an opening in front of the vent. Jaws none." 



CIRKOSTOMI. 



"Body elongate, compressed, scaleless, limbless. 

 Mouth a longitudinal fissure, with subrigid cirri on 

 each side, inferior. Vent at a short distance from 

 the extremity of the tail. A low ray less fin -like fold 



