qS ZOOTOMY. 



54. The composition of the hyoidean cornua : each con- 

 sists of a dorsal, somewhat triangular bone, the epi-hyal 

 {ep.hy), articulating at its apex with the inter-hyal, and at 

 its base united by suture to a second bone, the cerato-hyal 

 {c.hy), which forms the main part of the cornu, and is 

 connected ventrally with two small ossifications, the hypo- 

 hyals [fiJiy). 



55. The ■ branchiostegal rays (br.r), seven curved 

 rods of bone, articulated to about the upper three-fourths of 

 the posterior edge of the ceratohyal : the four superior rays 

 are connected with the outer face, the three inferior with 

 the inner face of the cerato-hyal. 



56. The uro-hyal or basi-branchiostegal (u.hy), a 

 median vertical plate of somewhat triangular form, inter- 

 posed between the hypo-hyals of opposite sides. 



XL In the branchial arches, make out 



57. The superior pharyngeal bones, two large 

 irregular bones, covered inferiorly with teeth, which lie, in 

 the entire fish, in the roof of the pharynx. These represent 

 the coalesced dorsal elements or pharyngo-branchialsof 

 the four anterior branchial arches. 



58. The epi-branchials, four slender bones standing 

 out horizontally from the outer edge of each superior 

 pharyngeal bone. 



59. The cerato-branchials, four larger bones on each 

 side, forming the main part of the four anterior branchial 

 arches : each is articulated at its dorsal end with the outer 

 (ventral) extremity of the corresponding epi-branchial, and 

 lakes a direction forwards, downwards, and slightly inwards. 



60. Each cerato-branchial is articulated below with a 

 hypo-branchial ossification, which passes forwards and 

 inwards. 



61. The basi-branchial, a median ventral ossification, 



