106 



LECTURE V. 



joint. In the Parrot-fishes and Diodons the articulation is quite 

 analogous to that of the mandible below with the tympanic pedicle. 

 In the Salamandroid fishes it is a fixed suture. In the Shad the 

 palatine articulates with the premaxillary as well as the maxillary. 

 In the Mormyrus the palatines meet, and unite together at the 

 median line. The posterior angle of the base of the palatine is 

 attached, in the Cod, by short and strong ligaments to the prefrontal. 

 The thin posterior and inner border of tlie bone is joined by liga- 

 ment to the ento-pterygoid, and its outer angle is dovetailed into the 

 pterygoid. The palatine contributes to form the floor of the orbit and 

 the roof of the mouth ; in many fishes it supports teeth, but is eden- 

 tulous in the Cod. It varies much in form in different species ; is 

 slender and elongated in the wide-mouthed voracious fishes, as the Pike, 

 and is short and broad in the broad-headed, small-mouthed fishes. 



The maxillary (hasmapophysis of nasal vertebra, fig. 30. 2l) is 

 usually a small edentulous bone*, concealed in a fold of the skin 

 between the palatine and premaxillary : it lies, in the Cod, posterior 

 to and parallel with the premaxillary, which it resembles in form, 

 but is longer and thinner in most osseous fishes : the expanded and 

 bifurcate end of the maxillary is produced inwards rather than up- 

 wards, and forms a socket on which the ascending or nasal process of 

 the premaxillary glides ; a posterior tubercle at this end is attached to 

 the palatine, and ligaments connect the same expanded end to the 

 iiasal, the turbinal, the vomer, and the premaxillary : the lower and 

 hinder expanded end of the bone is attached by strong elastic liga- 

 ment, in which a labial gristle is developed, to the coronoid process 

 of the lower jaw. 



In the Salmon tribe the maxillary is joined to the hinder and 

 lower end of the short premaxillary, forming with it a continuous arch, 

 and it supports teeth ; this normal and higher character of the 

 maxillary I prevails also in the Clupeoid fishes, and is here illustrated 

 in the great Sudis {fig- 36.). In the Plcc- 

 tognathi (Globe-fish and File-fish), the 

 maxillaries coalesce wholly or in part with 

 the premaxillaries. In the Lepidosteus the 

 contrary condition prevails : the premax- 

 illary and maxillary bones constitute, in- 

 deed, a single dentigerous arch or border 

 of the upper jaw, but are subdivided 



Disarticulated bones of palato- 

 maxillary arch (Arapainia gi'gfis). 



* The Os mj/stacejon of iclithyotomists. 



•(• Cuvier first recognised tlie special liomology of the ' os nuslacciiiii ' by ob- 

 serving its modifications in tlie salmon. 



