407 



cornu of the hyoid arch is attached; anteriorly and distally it 

 ends in an expanded plate, with which two bones are connected, in 

 front the tympanal, behind the symplectique. The distal end of 

 the suspensor is constituted by the triangular jugal, whose distal and 

 narrower extremity furnishes the condyle with which the mandible 

 is articulated. 



Fig. 7. Palatosuspensorial arch -of Gasterosteus from the inner side. HM. 

 Hyomandibular bone. Op. Its articular facet for the operculum. Po. Pre-oper- 

 culum. H. Articular surface for the styloid bone. Sy. Symplectic. P.Q. Palato- 

 quadrate arch. Pa. Palatine bone. Qu. Quadratum. Pt. Pterygoid. Mp. Me- 

 tapterygoid. 



The elongated styliform symplectique is received into a groove on 

 the posterior part of the inner surface of the jugal, and extends 

 nearly to the condyle. In front, the jugal articulates with the trans- 

 verse, and more or less with the pteryyoidien, which again are 

 anteriorly connected with the palatine. The flat tympanal is fitted 

 in between the pterygoidien, jugal, and temporal. 



Besides these numerous bones, there are four others which enter 

 less directly into the composition of the suspensorium. These are 

 the pre-opercule, a sort of splint-like bone which lies on the outer 

 and posterior faces of the temporal and jugal, and binds the two 

 together ; the opercule, which articulates with a special condyle 

 developed for it from the posterior edge of the temporal, above 

 the attachment of the hyoid ; the sousopercule, which lies in the 

 opercular membrane beneath this ; and lastly, the interopercule, the 

 lowest of all, and commonly more or less closely connected with the 

 angle of the lower jaw. 



