1904.] OSTEOLOGY OF CLUPEOID FISHES. 487 



the great size of the urohyal, an<l the enlargement of the hinder 

 parts for the support of the wall of the epibrarichial organ. The 

 structure of this organ has been described by Hyrtl {I. c. p. 4). 



The lower hypohyal is considerably larger than the upper. 

 The hind end of the giossohyal overlaps the front of the first 

 basibranchial, and a thin flake of bone projects from the back of 

 the first basibranchial ovei- the front of the second. A similar 



Text-fig. 143. 



ed.f. 



CJiaiios salmoueus, hyobrauchial .skeleton, Jorsal view. The epibraiicliials and 

 pharyugobrancbials of the right side are not shown. For explanation of 

 lettering see p. 493. 



flake extends from the second basil)ranchial over the fi'ont part 

 of the third. The anterior half of the giossohyal is cartilaginous, 

 but is covered by a membrane-bone Avhich is continued back over 

 the endosteal giossohyal. The third basibranchial is larger than 

 the first and second put together — as a rule the second basi- 

 branchial is the largest of the three. The third hypobranchials 

 are fused with the sides of the third basibranchial, Init the 

 boundary line between them is not oblitei'ated. 



There is a symphysis of considerable length between the two 

 fifth ceratobranchials, and from the front of this symphysis there 

 passes forward a bar of cartilage which, in front of the anterior 

 ends of the fourth ceratobranchials, enlai-ges into a roughly hexa- 

 o-onal plate. The separation of the anteiior ends of the fourth 

 aud fifth ceratobranchials is noteworthy. Behind the symphysis 

 of the fifth ceratobranchials is a horizontal tract of cartilage, 



