I30 ALUS. [Vol. XVIII. 



process, but extending somewhat farther along the rod-Hke part 

 of the bone, both anteriorly and posteriorly. The posterior, 

 rounded, free end of the process lies at a higher, more dorsal level 

 than the posterior end of the rod of the piece. The entire dorsal 

 surface of the process, and the adjoining dorsal surface of the rod, 

 are both covered with a layer of dermal bone, from which rise 

 numerous, strong, curved bristles. A bristly pad is thus formed 

 which is the inferior pharyngeal pad of the fish. The anterior 

 third of the piece lies, with its fellow of the opposite side of 

 the head, between the scoop-shaped ends of the fourth cerato- 

 branchials, the anterior ends of the two fifth ceratobranchials be- 

 ing enclosed in fibrous tissue and attached to, but not articulating 

 with, the hind edge of the median piece of cartilage that repre- 

 sents, apparently, the fused fourth hypobranchials. 



The Epibranchials of the first four arches decrease in length 

 from the first to the fourth. 



The First Epibranchial {EB, /) is a slender, semicylindrical 

 rod of bone, curved in two directions, the hollow of one curve 

 being presented dorsally, that of the other postero-mesially. It 

 has, slightly proximal to the middle of its length, a short, stout, 

 somewhat cylindrical process, directed mesially, or mesially and 

 forward, from the postero-mesial surface of the element. The 

 dorsal surface of the element is deeply grooved, the groove ex- 

 tending from the distal end of the bone forward to the anterior 

 edge of the postero-mesial process, where it turns mesially, and 

 leaves the bone, on its postero-mesial surface, in the angle between 

 the process and the anterior end of the shank of the bone. Both 

 ends of the bone are capped with cartilage, as is also the outer 

 end of its postero-mesial process. The anterior end of the ele- 

 ment articulates with the infrapharyngobranchial of the arch, the 

 postero-mesial process articulates with the suprapharyngobranchial 

 of the arch, and the hind end of the element articulates with the 

 corresponding ceratobranchial. 



The Second Epibranchial {EB, II) is a strongly curved bone 

 with an enlarged, flat, triangular, proximal end. Both ends of the 

 bone are capped with cartilage, the cap on the enlarged proximal 

 end having the shape of an elongated and solid figure 8. The 

 antero-lateral end of this 8-shaped cap articulates with the second 



