Nos. IAND2.] ANATOMY OF SCOMBER SCOMBER. 63 



deep angle, with a rounded bottom, which fits against the ventral 

 and anterior surfaces of the ventro-lateral process of the ethmoid, 

 and may perhaps be said to there articulate w^th it. 



No JuGAL bone, the supramaxillary bone of Sagemehl, is fovmd 

 in Scomber. 



The Prem axillary (PMX) is a curved bone of nearly the 

 same length as the maxillary. Its anterior end is flat, and irregu- 

 larly triangular in shape, the point of the triangle directed upward, 

 or upward and backw^ard, and forming the ascending process of 

 the bone. Posterior to this triangular head of the bone, the pre- 

 maxillary is slender, tapering gradually to a blunt and slightly 

 enlarged hind end. The ventral edge of the bone is furnished, 

 throughout its entire length, with small sharp teeth. In the angle 

 between the posterior edge of the ascending process and the dorsal 

 edge of the shank of the bone, there is a small projecting edge of 

 bone, which presents articular surfaces both internally and exter- 

 nall}^ The external surface is slightly concave, the internal one 

 slightly convex, and they fit in between, and articulate with the 

 two articular surfaces on the outer surface of the maxillary, as 

 already described. Immediately dorso-anterior to the articular 

 edge there is a sharp edge, or even a sharp process of bone, which 

 gives partial attachment to a band of fibrous tissue, somew^hat liga- 

 ■ mentous in character, which connects the bone, and also the 

 maxillary, with the inner surface of the nasal near its anterior end. 

 On the internal surface of the premaxillary, near its anterior edge, 

 there is a small articular surface, covered with fibrous or fibro- 

 cartilaginous tissue, which gives articulation to the anterior articu- 

 lar edge of the maxillary. The anterior edge of the bone is slightly 

 roughened and forms the surface of insertion for the tough fibrous 

 tissues that bind the bone to its fellow of the opposite side of the 

 head. 



The maxillary, premaxillary and rostrale are strongly bound 

 together by fibrous or ligamentous tissues, and the premaxillary 

 is bound by similar tissue to the corresponding bone of the oppo- 

 site side of the head. The five elements thus form a single piece, 

 between the separate parts of which but little movement is pos- 

 sible. The piece forms the upper jaw of the fish, and is capable of a 

 certain amount of movement upon the anterior end of the cranium. 



