The =pelvic girdle= in the Cod as in other Teleosteans is entirely absent, its place being taken by the enlarged basi-pterygia of the fins. THE PELVIC FINS. These have a very anomalous position in the Cod, being attached to the throat in front of the pectoral girdle. Each consists of a basal portion, the =basi-pterygium=, and of a number of dermal rays. The basi-pterygium consists of an expanded ventral portion which meets its fellow below in the middle line, and to which the rays are attached, and of an inwardly-directed dorsal portion which also meets its fellow and is imbedded in the flesh. The rays are six in number and are long slender structures similar to those of the other fins. FOOTNOTES: [35] See T.J. Parker's _Zootomy_, London, 1884, p. 86. [36] See W.K. Parker and G.T. Bettany, _The Morphology of the Skull_, London, 1877, chap. 3. [37] T.J. Parker, _Zootomy_, London, 1884, p. 91. [38] According to G. Swirski, _Schultergurtel des Hechtes_, Dorpat, 1880, the true coracoid is aborted, and the so-called coracoid of Teleosteans is really the precoracoid. CHAPTER VIII. GENERAL ACCOUNT OF THE SKELETON IN FISHES[39]. EXOSKELETON. The most primitive type of exoskeleton is that found in Elasmobranchs and formed of =placoid= scales; these are tooth-like structures consisting of dentine and bone capped with enamel, and have been already described (p. 4). In most Elasmobranchs they are small and their distribution is fairly uniform, but in the Thornback skate, _Raia clavata_, they have the form of larger, more scattered spines. In adult Holocephali and in _Polyodon_ and _Torpedo_ there is no exoskeleton, in young Holocephali, however, there are a few small dorsal ossifications. The plates or scales of many Ganoids may have been formed by the gradual fusion of elements similar to these placoid scales, and often bear a number of little tooth-like processes. In _Lepidosteus_, _Polypterus_, and many extinct species, these _ganoid_ scales, which are rhomboidal in form and united to one another by a peg and socket articulation, enclose the body in a complete armour. In _Trissolepis_ part of the tail is covered by rhomboidal scales, while rounded scales cover the trunk and remainder of the tail. _Acipenser_ and _Scaphirhynchus_ have large dermal bony plates which are not rhomboidal in shape and do not cover the whole body. In _Acipenser_ a single row extends along the middle of the back and two along each side.