The gills of the Teleosteans as well as of the Ganoids are supported by a series of solid cartilaginous or horny pointed rods, arranged along the convex edges of the branchial arches. Arches bearing a complete gill have two series of those rods, one along each edge; those with uniserial gills bear one row of rods only. The rods are not part of the arch, but fixed in its integument, the several rods of one row corresponding to those of the other, forming pairs (_feuillet_, Cuvier) (Fig. 59). Each rod is covered by a loose mucous membrane passing from one rod to its fellow opposite, which again is finely transversely plaited, the general surface being greatly increased by these plaits. In most Teleostei the branchial lamellæ are compressed, and taper towards their free end, but in the Lophobranchs their base is attenuated and the end enlarged. The mucous membrane contains the finest terminations of the vessels, which, being very superficial, impart the blood-red colour to living gills. The _Arteria branchialis_, the course of which lies in the open canal in the convexity of the branchial arch, emits a branch (_a_) for every pair of lamellæ which ascends (_b_) along the inner edge of the lamella, and supplies every one of the transverse plaits with a branchlet. The latter break up into a fine net of capillaries, from which the oxygenised blood is collected into venous branchlets, returning by the venous branch (_d_), which occupies the outer edge of the lamella. [Illustration: Fig. 59.--A pair of branchial lamellæ (magnified) of the Perch. _a_, Branch of Arteria branchialis; _b_, Ascending branch of the same; _c_, Branch of Vena branchialis; _d_, Descending branch of the same; _e_, Transverse section through the branchial arch.] The so-called _Pseudobranchiæ_ (Fig. 60) are the remains of an anterior gill which had respiratory functions during the embryonic life of the individuals. By a change in the circulatory system these organs have lost those functions, and appear in the adult fish as retia mirabilia, as they receive oxygenised blood, which, after having passed through their capillary system, is carried to other parts of the head. In Palæichthyes the pseudobranchia is a rete mirabile caroticum for the brain and eye; in Teleosteans a rete mirabile ophthalmicum only. Pseudobranchiæ are as frequently absent as present in Chondropterygians as well as Teleosteans. As to the Ganoids, they occur in _Ceratodus_, _Acipenser_, _Polyodon_, and _Lepidosteus_, and are absent in _Lepidosiren_, _Protopterus_, _Scaphirhynchus_, _Polypterus_, and _Amia_.