SEA-FISHERIES LABORATORY. 179 



Inter-hyal (I.Hy., figs. 5 and 6). — Possibly a sesa- 

 moid bone developed in the inter-hyal ligament and not 

 homologous with the other segments of the hyoid. This 

 bone is incorrectly called by some authors the stylo-hyal — 

 a term really a synonym of the pharyngo-hyal, represented 

 in most fishes by the hyomandibnlar. The inter-hyal of 

 the Plaice consists of a central bony rod with cartilaginous 

 extremities articulating with the hyoid and symplectic 

 and inter-operculum, as already indicated. Below the 

 attachment of the inter-hyal to the upper epi-hyal is seen 

 the prominence which is also connected with the inter- 

 operculum. 



Branchiostegal Rays (Br.R.). — There are the usual 7 

 of these rays, the first on each side meeting at their free 

 extremities, and being closely bound together by strong 

 fibrous connective tissue, appear to fuse. They are not all 

 attached at the same plane as shown in the figure. The 

 first 3 articulate with the cerato-hyal, the last 4 at about 

 the junction of the 2 epi-hyals. The last, however, is 

 always attached to the upper or bony epi-hyal. The rays 

 have cartilaginous extremities, but otherwise consist of a 

 transparent milky coloured bone. The first two cross and 

 lie under the others in the living state. 



Eyeless Side. 



The hyoid bar is slightly shorter and not quite so 

 robust. The first pair of apparently fused rays are drawn 

 over to the eyeless side as shown in the figure. The most 

 conspicuous difference is in the branchiostegal rays, which 

 are, except the first, uniformly shorter and not so curved. 

 The length and curve are faithfully represented in the 

 figure, 



