i8g6. 



THE TEETH OF FISHES. 



389 



grooves on their upper or buccal surface. The vomerine teeth in 

 Chimava are relatively larger and more important than in Dipnoi, and 

 they touch and overlap the palato-pterygoid teeth. 



In the osseous fishes (Teleostei and Ganoidei Holostei) the dental 

 system is well developed, although exceptionally, as in the pipe-fish 

 (Sygnathns) and sea-horse {Hippocampus), teeth may be altogether 

 wanting. Teeth are usually present on the premaxilla and dentary, 

 and frequently also on the vomer and palatine, and on the branchial 

 arches. The maxilla, pterygoid, parasphenoid and splenial bones 

 bear teeth in the Ganoidei ; but in the Teleostei maxillary teeth are 

 confined to the Physostomi, the pterygoid and parasphenoid bones 



Fig. 16. — View of suctorial disc of the mouth of the lamprey, Petromyzon 

 marinus. Fig. 17. — Section, greatly enlarged, of a tooth, /, of the lamprey, with its 

 two successors, V and t" ; p, the dental papilla. Fig. 18. — Upper and lower jaws, 

 greatly enlarged, of the larva of the sterlet, Acipenser ruthenus (after Parker, Phil. 

 Trans., 1S82). Fig. 19.— Teeth of Ceratodus forsteri: v, vomerine; /, palatopterygoid ; 

 s, splenial teeth. Fig. 20.— Section of a portion of the pharyngeal bone of Labrus 

 (after Owen) : t, tooth in use; V , its successor. Figs. 21 and 22. — The upper (21) 

 and lower (22) pharyngeal bones of Scants viuricatus : A, anterior end ; P, posterior 

 end ; s, space occupied by developing teeth which have not yet coalesced or 

 become adherent to the bone. 



are only exceptionally dentigerous, <?.£•., Elops and AlbuLi, and splenial 

 teeth do not occur at all. In the living bony Ganoidei all the bones 

 related to the mucous membrane of the mouth are richly beset with 



