Nos. IAND2.] ANATOMY OF SCOMBER SCOMBER. j-q 



The Clavicle {CL, Figs. 45-51) is a long, curved bone, the 

 ventral and larger part of which may be described as a long flat 

 oval and pointed piece of bone folded back upon itself, along its 

 longest axis, in such a way as to form, on its posterior aspect, a 

 deep angular groove, of about 70°, with a rounded bottom. That 

 part of the bone that forms the mesial wall of this groove is 

 directed almost directly backward. It is thinner and less strong 

 than the part that forms the antero-lateral wall, which is directed 

 outward and backward. The hind edge of the mesial wall is 

 deeply cut out, near its dorsal end, and there forms part of the 

 bounding wall of a large opening. This ventral, grooved part of 

 the clavicle extends almost to the dorsal end of the bone; and 

 opposite the dorsal end of the groove there is usually, on the 

 lateral edge of the antero-lateral wall of the bone, which is here 

 greatly reduced in height, a slight eminence which seems to 

 mark the dorsal end of some definite morphological part of 

 the bone. The ventral end of the supraclavicular, in its natural 

 position, lies slightly above this eminence, and the two bones 

 are here connected by fibrous tissues. The lateral edge of the 

 clavicle, ventral to this point, is thickened and grooved for a 

 certain distance, the groove giving attachment to the dermal tis- 

 sues of the region. 



That part of the clavicle that lies dorsal to its grooved part has 

 much the appearance of a separate formation, added to and fused 

 with the main ventral part. The dorsal edge of this apparently 

 added portion is curved, and is, near its anterior end, deeply 

 notched, the notch lodging the occipito-supraclavicular ligament 

 as that ligament passes outward to its insertion on the inner sur- 

 face of the supraclavicular. That portion of this part of the bone 

 that lies in front of the notch, forms a short stout process directed 

 upward and forward. It forms the actual proximal end of the 

 clavicle, bears on its end a slender spine-like process directed 

 dorsally or dorsally and backward, and lies internal to the ventral 

 end of the thickened part of the supraclavicular. The part pos- 

 terior to the notch forms a relatively large, flat process, which pro- 

 jects almost directly backward and is slightly convex on its outer, 

 and concave on its inner surface. Its dorsal edge is strongly 

 rounded, and presents a large, shallow, rounded indentation, which 



