Nos. IAND2.] ANATOMY OF SCOMBER SCOMBER. 157 



tral edge of the body of the articular overlaps mesially the dorsal 

 edge of the ventral arm of the dentary, its anterior end extending 

 forward beyond the base of the arm of the dentary into the hollow 

 of the bone itself. On the dorsal edge of the hind end of the 

 articular, which end often projects backward as a sort of posterior 

 process, there is a transverse articular surface, concave in the 

 longitudinal direction of the bone and convex in the transverse 

 direction. The hind edge of this surface projects upward, as a 

 hook-like process, and fits into a corresponding recess on the hind 

 edge of the articular head of the Cjuadrate. The articular surface 

 is lined with cartilage. From the anterior edge of this cartilage, 

 on the inner surface of the bone, a slight rounded line, or some- 

 times simply a surface marking on the bone, runs forward, and, 

 beyond the bases of the two large dorsal and ventral processes of 

 the bone, becomes a slight blunt process directed forward. The 

 flat anterior end of this process abuts against and is continuous 

 with the hind end of IMeckel's cartilage, the rounded line thus prob- 

 ably indicating the position of an ossified portion of the cartilage. 



The articular is traversed by the posterior part of the mandib- 

 ular lateral canal. 



The Angular (ANG) is a small irregular bone that fits against 

 the mesial surface of the ventral edge of the articular, near its 

 hind end and immediately antero-ventral to the articular facet 

 for the quadrate. The ventral edge of the bone usually projects 

 downward beyond the ventral edge of the articular, and at or near 

 its hind end it is thickened and rounded into a blunt process which 

 gives insertion to the ligament that connects the mandible with the 

 interoperculum. The bone lies wholly ventral to the hind end of the 

 line that indicates the posterior continuation of Meckel's cartilage, 

 and is not traversed by any part of the lateral canal. It occupies, 

 approximately, the position of ossicle a in Amia; but whether it is 

 or is not, in Scomber, in part, or in whole, of cartilaginous origin 

 was not investigated. 



The Dentary (D) is a strong, V-shaped bone, the external 

 margins of the adjoining edges of the V being connected for a 

 certain distance by a thin web of bone. The dorsal edge of the 

 dorsal arm of the A^ is lined with a single row of small, sharp teeth. 

 The ventral edge of the same arm is grooved, the anterior end of 



