470 SYDNEY E. JOHNSON 



4. Hyoidean apparatus 



The interhyal (ihy.) is a short, slender rod connecting the 

 epihyal with the suspensory apparatus. The lower or posterior 

 end is expanded and makes a rather strong articulation with the 

 superior end of the epihyal (figs. 11 and 4). 



The epihyal (ephy.) is a triangular expansion of bone, the 

 shape and attachments of which are shown in figure 11. The 

 bone is thicker and stronger near its superior end. 



The main part of the cornu is formed by the ceratohyal (chy.). 

 The anterior margin of this bone is slightly concave while the 

 posterior border is interrupted by an angular projection near its 

 superior end (fig. 11). 



The hyohyals (hhy.) and the glossohyal (ghy.) constitute a 

 group of ossifications connecting the two opposite ceratohyals 

 below. 



The hranchiostegal rays (br.) are six slender rods of bone, on 

 each side. Their attached ends are flattened and considerably 

 expanded. The two superior rays are attached to the outer 

 face of the epihyal, the next two, to the outer surface of the 

 ceratohyal, and the two inferior rays articulate with the inner 

 surface of the ceratohyal (fig. 11). 



5. The branchial arches 



The superior pharyngeals (s. ph.) of each side are coossified to 

 form two solid bones which, in turn, unite firmly along the median 

 line. The under surface of these bones is well provided with 

 long viUiform teeth (fig. 12). 



The epibranchials (epbr.), four on each side, are slender rods 

 of bone which join the superior pharyngeals medially with the 

 four ceratobranchials (cbr.) laterally. The latter are elongated 

 rods which curve around the pharynx, the three anterior bones 

 uniting with the hypobranchials (hbr.) ventrally and the posterior 

 one with the posterior basibranchial (fig. 12). 



The basibranchials (bbr.) are poorly defined and incompletely 

 ossified. They intervene ventrally between the hypobranchials 

 and the posterior ceratobranchials of the opposite sides (fig. 12). 



