SKELETON. 59 



irregularly-shaped epihranchial (61). In the fourth arch the 

 hypobrancliial 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 dis- 

 tinguished as the upper phai^yngeal hones. Only the cerato- 

 branchial 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, wliich do not form part of the skeleton. 



The scapular or humeral arch is suspended from the skull 

 by tha (suprascapula) post-temporal (46), which, in the Perch, 

 is attached by a triple prong to the occipital and mastoid bones. 

 Then follows the {scapula) supraclavicula (47), and the arch is 

 completed below by the union of the large (coracoid) clavi- 

 cula (48) with its fellow. Two flat bones (51, 52), each with 

 a vacuity, attached to the clavicle have been determined as 

 the (radius and ulna) coracoid and scapula of higher verte- 

 brates, and the two series of small bones (53) intervening 

 between the forearm and the fin as carpals and metacarpals, 

 A two-jointed appendage the (epicoracoid) post-clavicida, is 

 attached to the clavicle : its upper piece (49) is broad and 

 lamelliform, its lower (50) styliform and pomted. 



The ventral fins are articulated to a pair of flat triangular 

 bones, the puhic bones (80). 



The bones of the skull of the fish have received so many 

 different interpretations that no two accounts agree in their 

 nomenclature, so that their study is a matter of considerable 

 difficulty to the beginner. The following synonymic table will 

 tend to overcome difficulties arising from this cause ; it contains 

 the terms used by Cuvier, those introduced by Owen, and finally 

 the nomenclature of Stannius, Huxley, and Parker. Those 

 adopted in the present work are printed in italics. The 



