TYPES OF FISHES. 
23 
which the hinder half of the skull is completely roofed over 
by bone ; while the teeth in many cases exhibit a curious 
infolded arrangement from which the group derives its name. 
The last bay (ISTo. V.), on the west side of the Central Hall, Bay V. 
is devoted to the display of the form and structure of Fishes, Wishes and 
and of that remarkable little creature the Lancelet, formerly Lancelet. 
included among the Fishes, but now regarded as the representa- 
tive of a class of itself — the Ceiolialocliorda. 
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 — 
Fig. 5. — Side View of Skull of Comb-Toothed Shaek (after Wiedersheim). 
pg, pterygo-quadrate cartilage (forming the functional upper jaw) ; md, mandi- 
bular cartilage, the functional lower jaw ; nh, nasal capsule ; orh, orbit ; 
r, rostrum ; m^:, backbone, or vertebral column ; >J< postorbital articulation 
of the upper jaw with the cranium. 
mainly cartilaginous — of the Great Blue Shark (Carcharodon 
rondeletii), fig. 4, which occupies the greater portion of this 
case. It should be noted that the jaws do not correspond with 
those of the higher Vertebrates ; and particular attention should 
be devoted to the structure and arrangement of the arches 
supporting the gills. 
In the left 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-lisli, in 
wliich tlie skeleton of the (in consists of a median joiuUul axis, 
