(_c_) Each of the five =branchial arches= is a hoop, incomplete above and formed of four or more pieces of cartilage. The most dorsal elements, the =pharyngo-branchials=, are flattened, pointed plates whose free inner ends run obliquely backwards, and terminate below the vertebral column. They are connected at their outer ends with the short broad =epi-branchials= (fig. 6, 16) which lie at the sides of the pharynx. From the epi-branchials arise the long =cerato branchials= (fig. 6, 17) which run forwards and inwards along the ventral wall of the pharynx. The first four cerato-branchials are connected with small rods, the =hypo-branchials=, which run backwards to meet one another in the middle line. The last two pairs of hypo-branchials and the fifth cerato-branchials are connected with a broad median plate, the =basibranchial=. Along the outer sides of the second, third and fourth cerato-branchials are found elongated curved rods, the =extra-branchials= (fig. 6, 19). The epi-branchials and cerato-branchials bear gill rays along their posterior borders.
The =dorsal fins= have a skeleton consisting of a series of short cartilaginous rods, the =basals= or basalia, which slope obliquely backwards. Their bases are imbedded in the muscles of the back, while their free ends bear a number of small polygonal cartilaginous plates, the =radials= or radiale. Associated with this cartilaginous skeleton are a number of long slender horny fibres, the fin-rays, which have been already referred to in connection with the exoskeleton. The skeleton of the other median fins mainly consists of these fibres, the cartilaginous portion being reduced or absent.
This includes the skeleton of the two pairs of limbs and of their respective girdles.
THE PECTORAL GIRDLE forms a crescent-shaped hoop of cartilage, incomplete above and lying just behind the visceral skeleton. The mid-ventral part of the hoop is the thinnest portion, and is drawn out in front into a short rounded process which is cupped dorsally and supports part of the floor of the pericardium (fig. 7, 1). On each side of this flattened mid-ventral portion the arch becomes very thick and bears on its outer border a surface with which the three basal cartilages of the fin articulate. The dorsal ends or scapular portions of the girdle form a pair of gradually tapering horns.