The _branchial arches_ (Figs. 25 and 27) are enclosed within the hyoid arch, with which they are closely connected at the base. They are five in number, of which four bear gills, whilst the fifth (56) remains dwarfed, is beset with teeth, and called the _lower pharyngeal_ bone. The arches adhere by their lower extremities to a chain of ossicles (53, 54, 55), _basibranchials_, and, curving as they ascend, nearly meet at the base of the cranium, to which they are attached by a layer of ligamentous and cellular tissue. Each of the first three branchial arches consists of four pieces movably connected with one another. The lowest is the _hypobranchial_ (57), the next much longer one (58) the _cerato-branchial_, 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 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_, which do not form part of the skeleton. The _scapular_ or _humeral arch_ is suspended from the skull by the (_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_) _clavicula_ (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 vertebrates, 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_) _postclavicula_, is attached to the clavicle: its upper piece (49) is broad and lamelliform, its lower (50) styliform and pointed. The ventral fins are articulated to a pair of flat triangular bones, the _pubic_ 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 numbers refer to the figures in the accompanying woodcuts (Figs. 23–27). _Cuvier._ _Owen._ _Stannius._ _Huxley, Parker, etc._