The last bay (No. V) on the west side of the Central Hall is devoted to the display of the form and structure of Fishes. The wall-case on the left side of this bay exhibits the external form of several characteristic types of Fishes, such as the Pike, Cod, Turbot, Dog-fish, and Skate, with the names of the various fins affixed. A striking specimen is the skeleton--mainly cartilaginous--of the Great Blue Shark (_Carcharodon rondeletii_), fig. 10, which occupies the greater portion of this case. It should be noted that, as in all Sharks and Rays, the upper jaw does not correspond with that of the higher Vertebrates; and particular attention should be devoted to the structure and arrangement of the arches supporting the gills. In the south side of the table-case in this bay are shown a number of dissections, mounted in spirit, displaying the different types of skeletal structure presented by the fins in various groups of Fishes. One of the most remarkable of these types occurs in _Ceratodus forsteri_, the Queensland Lung-fish, in which the skeleton of the fin consists of a central jointed rod, from each side of which diverge narrower jointed rods. Alongside are specimens showing special modifications of certain fins, as in the Flying Fish (fig. 11) and Flying Gurnard (fig. 12), for the purpose of sustaining the body in the air, or, as in _Pentanemus_, to serve as organs of touch. Specimens of the West Indian Goby and the Lump-Sucker show modifications of the pelvic fins in connection with a sucker on the lower surface of the body; while other preparations display the pectoral (_Doras_) and pelvic fins (_Monocentris_) reduced to the condition of saw-like spines. The structure of the skull of Fishes is illustrated in another part of the same side of this case. From this the visitor may learn how the primitive cartilaginous skull of the Sharks (fig. 10), Rays, Chimæras, and Lung-fishes has been gradually modified, by the addition of superficial sheathing-bones, into the bony skull of modern Fishes, such as the Cod and Perch. [Illustration: FIG. 11.--THE FLYING FISH (_Exocœtus_). FIG. 12.--THE FLYING GURNARD (_Dactylopterus_).]