Vil 
THE TELEOSTOMES 
ALL fishes not to be grouped among Sharks, Chime- 
roids or Lung-fishes, have been included in the fourth 
sub-class, Teleostomi. In this are to be merged the two 
time-honoured groups, Ganoids* and Teleosts, since it is 
now found that there are absolutely no structures of the 
one group that are not possessed by members of the other. 
The terms, therefore, “Ganoid” and “Teleost,” must 
be used in a popular and convenient, rather than in an 
- accurate sense ; the former to denote the “old-fashioned ” 
Teleostome, with its rhombic bony body plates, and carti- 
laginous endoskeleton; the latter, the modern “ bony fish,” 
with rounded, horn-like scales and its calcified endo- 
skeleton. 
Teleostomes present so wide a range of variation that 
it becomes exceedingly difficult to include in a single 
definition their minor structural characters. 
As a basis for the comparison of the Teleostomes, the 
characteristic structures of a single type, ¢.g. the Perch, 
might conveniently be taken. From these conditions, 
typical of a modern and highly specialized form, the simple 
structures of the ancient, more primitive, and ancestral 
Ganoids may afterward be readily understood. 
* The term Ganoid, as here used (as far as p. 147), includes the Crossopte- 
rygians as well. 
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