SEA-FISHERIES LABORATORY. 173 



articular immediately in front of the quadrate articulation 

 for the M. adductor mandibulse is much more marked on 

 this side, where the muscle is naturally larger and, 

 further, the distortion of the jaws to the eyeless side is 

 assisted by a tendon from it inserted into the maxilla. 

 The dentary of this side bore 22 teeth, as against 3 on the 

 right side. 



Maxilla. — Distinctly larger and more curved than the 

 right but not so robust. At about a third from the head 

 on the posterior edge is an eminence for the attachment of 

 a stout tendon arising in connection with the M. adductor 

 mandibulse, and the action of which tends to draw the 

 jaws towards the eyeless side. This eminence and tendon 

 are not conspicuous on the ocular side, and indeed in the 

 Sole, where the ocular is also the right side, the tendon is 

 stated by Cunningham! to be absent on the eyeless side, 

 although the muscle is said to be larger on that side. The 

 eminence is figured, and the muscle described by Tra- 

 quair,J who calls the latter the Retractor Maxilla?.* At 

 the head of the maxilla on the posterior side the bone 

 articulates directly with the free anterior extremity of the 

 palatine instead of by the interposition of a short liga- 

 ment. The cap of cartilage gliding over and above the 

 head of the vomer is larger and the terminal free facet is 

 also more extensive. The whole action of the jaw appa- 

 ratus is markedly asymmetrical owing to the unpaired 

 mesethmoid prominence separating the two maxillary 

 facets being obliquely set towards the right. Hence when 

 the maxillae are depressed they follow an oblique direction 

 towards the left or eyeless side. The articulation of the 

 maxilla with the pre-maxilla is also modified on this side. 

 On account of the motion of the jaws towards the left the 



f The Common Sole. Plymouth, 1890, p. 48. J Op. cit., p. 279, Tab. 30. 

 * Cp. also Allis, Jour. Morph., xii., pp, 552 and 576, 



