The branchiostegal rays of the two sides are united in front by an unpaired membrane bone, the basi-branchiostegal (fig. 11, 36).
These are the bones connected with respiration—the operculum, the branchiostegal rays, the branchial arches, and others.
The mouth and branchial cavity were very much distended, rounding out and distorting the whole hyoid and branchiostegal region.
To the cerato-hyal are attached a series of seven strong curved cylindrical rods, the branchiostegal rays.