53 



Hyoid and branchial arches of Perch. 



hypobranchial (57), the next much larger one the ceratobranchial 

 (58), and above this, a slender and a short irregularly-shaped 

 epibranchial (61). In the fourth arch the hypobranchial is absent. 

 The uppermost of these segments (62), especially of the fourth 

 arch, are dilated and more or less confluent ; they are beset with 

 fine teeth, and generally distinguished as the upper pharyngeal 

 bones. Only the ceratobranchial is represented in the fifth arch 

 or lower pharyngeal. On their outer convex side the branchial 

 segments are grooved for the reception of large blood-vessels 

 and nerves ; on the inner side they support horny processes (63), 

 called the gill-rakers, which do not form part of the skeleton. 



The scapular or humeral arch (fig. 39) is suspended from the 

 skull by the suprascapula (46) ; then follows the scapula (47), 

 and the arch is completed below by the union of the coracoid (48) 

 with its fellow. Two flat bones (51, 52) attached to the coracoid may 

 be regarded as radius and ulna ; and two series of small bones (53) 

 between the forearm and the fin (54) as carpals and metacarpals. 

 A two-jointed appendage, the epicoracoid (49, 50), is attached to 

 the clavicle. 



The pelvic arch (fig. 37) is reduced to a pair of flat bones, called 

 pubic bones (80), to which the ventral fins (81) are articulated. 



