98 THE VERTEBRATE SKELETON. 



articulates dorsally with the basi-occipital and dorsolaterally 

 with the pro-otics and opisthotics, in front it articulates 

 dorsally with the lateral ethmoid and ventrally with the 

 vomer. At the sides of the parasphenoid are the small ali- 

 sphenoids articulating above with the postf rentals, in front 

 with the frontals, and behind with the pro-otics. 



The vomer is an unpaired bone lying immediately in front 

 of the parasphenoid. In front it terminates with a thickened 

 curved margin bearing several rows of small teeth ; behind 

 it tapers out into a long process which underlies the anterior 

 part of the parasphenoid. Immediately dorsal to the vomer 

 is another median bone, the median ethmoid] this is truncated 

 in front and tapers out behind into a process which fits into a 

 groove on the ventral side of the frontal. 



BONES IN CONNECTION WITH THE UPPER JAW. 



These bear a close resemblance to those of the Salmon. 

 The most anterior bone is the premaxilla, a thick curved bone 

 meeting its fellow in the middle line. The point of junction 

 of the two is drawn out into a short process, and the oral 

 surface is thickly covered with small teeth. The dorsal ends 

 of the premaxillae are seen in the fresh skull to meet a large 

 patch of cartilage. Behind the premaxilla is the maxilla, a 

 long rod-like toothless bone, somewhat expanded at the upper 

 end where it articulates with the premaxilla and vomer. 



Articulating in front with the anterior end of the maxilla 

 and with the lateral ethmoid is a very irregular bone, the 

 palatine (fig. 12, 1); it articulates behind with two flat 

 bones, the pterygoid and meso-pterygoid. The ptery- 

 goid is united behind with two more bones, the quadrate 

 (fig. 12, 4) and meta-pterygoid. The quadrate is a rather 

 stout irregular bone, bearing on its lower surface a promi- 

 nent saddle-shaped articulating surface for the mandible. 

 The palatine, pterygoid and quadrate bones are the ossified 



