PEDIGREE OF FISHES. 257 
well-known observations, the homologous parts of the 
Ganoids are related either as progressive developments 
or as reductions. Huxley has also prepared the way for 
a correct apprehension of these relations. To be fully 
convinced of this, detailed study is certainly requisite ; 
for in its absence it is impossible to imagine, how in the 
Elasmobranchii the true branchial apparatus is wanting, 
and how the cartilaginous arch, which, in them, replaces 
the gills, is applied in the Ganoids, partly as the palate, 
and partly as the attachment for the true lower jaw, while 
the internal gills of the former, become the external 
gills of the latter ; how in the skeleton of the anterior 
extremities, a gradual simplification may be exhibited, 
step by step, from the sharks and rays to the Ganoids, 
and especially the sturgeon,—a process of which the two 
extremes are reached in the Teleostei on the one side 
and the higher Vertebrata on the other—in the latter 
in the multiform perfection of the arm and hand. 
Of the Ganoids only scattered remnants survive, the 
sturgeon family and some few American and African 
genera, of which, as Riitimeyer says, a flight into fresh 
water has been the salvation. They just suffice to 
explain the relation of this once extraordinarily exten- 
sive group, to the Elasmobranchii as well as the Teleostei. 
In the Teleostei, the metamorphosis of the organ- 
ization of the Elasmobranchii initiated in the Ganoids, 
is carried yet further. It is only with great qualifica- 
tion that they can be termed “ more highly developed,” 
in the skeleton perhaps, to which older zoologists attri- 
buted too much importance, Brain, heart, the form of 
the extremities, and the reproductive system, are indeed 
distinct developments which, in combination with the 
external shape and integuments, have exhibited great 
