172 
ACANTHOPTERYGII. — LOPHIAD^. 
fishes, the law which assigns one sphere of action 
to the Class, is much more uniform in its opera- 
tion, admitting of scarcely any exception. 
This law is not, however, quite universal : there || i 
are a few fishes which invade the domain of the 
birds, as the proper FJying-fishes {Exoccetus\ here- 
after to be noticed, and some species {Dactylo- 
pterus) in the Family of the Gurnards ; and in the 
LophiadcE^ the Family which we have now to de- 
scribe, a still rarer aberration of habit is found | ' 
in fishes which are enabled to leave the water, ; ; 
and crawl about on land, for hours, or even days 
together, thus emu- 
lating the terrestrial 
manners of quadru- 
peds. 
To enable them to 
do this, two peculiari- 
ties of structure have 
been conferred upon 
them : the one modi- 
fying the organs of mo- 
tion, the other those 
of respiration. The 
pectoral and the ven- 
tral fins in fishes cor- 
respond with the limbs 
of other vertebrate 
BONES OF PECTORAL FIN OF animals, the former 
LOPHius. representing the arms, 
fore-legs or wings, the latter the hinder extremi- 
ties. And this analogy, which is structural, 
is not at all affected by the relative position 
of these members, even though the ventrals 
should be, as in the Family before us, situated 
