24 
CENTRAL HALL. 
from either side of which diverge narrower jointed rods. 
Alongside are specimens showing special modifications of 
certain fins, as in the Flying-Fish and Flying-Gurnard, 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), or pelvic 
fins {Monocentris) reduced to the condition of saw-like spines. 
Fig 6.— Jaw of Port Jackson Shark. 
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. 5), 
Rays, Chim^eras, 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. 
The north side of the table-case in Bay V. is mainly devoted 
to the display of the different types of scales, spines, and teeth, 
found among fishes. In one corner are the bony (" ganoid ") 
