Xos. iAND-2.] ANATOMY OF SCOMBER SCOMBER. 139 



surface of the element, this closed canal becomes an open channel 

 which runs proximally to the end of the piece, lying always in the 

 line between the two ossifications. 



A laminar process, arising from the superficial layers of the 

 bone, projects backward from the proximal end of the lateral sur- 

 face of the ventral ossification, and usually overlaps to a certain 

 extent, the adjoining edge of the ceratohyal. 



The two ossifications of the Ceratohyal (CH) are one distal 

 and the other proximal. They are separated by a transverse inter- 

 space of cartilage which is partly or wholly interrupted, near its 

 middle portion, by long, splint processes, which project from the 

 ends of both ossifications and firmly interlock. The distal ossifi- 

 cation is somewhat longer than the proximal one, and the two 

 together form a single piece with a flat, blade-like portion and a 

 somewhat stouter, but relatively broad, handle. The proximal 

 end of the piece is bluntly pointed, and has, slightly distal to the 

 blunt end, on the dorsal edge of the piece, a slight depression which 

 forms an articular facet for the distal end of the epihyal. It lies 

 somew^hat on the lateral surface of the piece, and is lined with 

 what seems to be fibrous or fibro-cartilaginous tissue, and not with 

 true cartilage. Slightly distal to it, near the middle line of the 

 lateral surface of the piece, there is a more or less pronounced de- 

 pression w^hich forms the surface of origin not only of a short 

 strong ligament that has its insertion on the inner surface of the 

 dorsal edge of the interoperculum, but also of fibrous tissue that 

 has its insertion mainly on the inner surface of the interoperculum 

 near its anterior end. From this latter point a fibrous band 

 runs downward and forward to the inner surface of the hind 

 end of the angular. The strongly developed ligamentum man- 

 dibulo-hyoideum of Aniia is thus either wholly wanting in Scom- 

 ber, or it is represented in fibrous tissues a part of which arise 

 from the ceratohyal and are inserted on the interoperculum, while 

 the other parts arise from the interoperculum and are inserted on 

 the angular. 



Dorsal to the depression that gives insertion to the fibrous and 

 ligamentous tissues above described, there is, along the outer sur- 

 face of the ceratohyal, a deep longitudinal groove. Running dis- 

 tally this groove crosses the interspace of cartilage between the 



