282
THE BIOLOGY‘ OF FISHES
[
develop gill—r‘äkers. “ _ It may; be also that the great-difference '
f
in the size -and development of the Leptocephali comes. in
:
part from the difference in ”the amount of food they
_
get into their months,
.
-
'
«
»
The principal function of thegill—rakers is to protect
%
the delicate gill—laments—as one might-conclude from the
law of action and reaction.
It is only sècondarily that they '
are
the food.
The
“
selection
” of the latter
_
depends-on the senses, and a sh, we may be sure, doesnot
trouble to consul—t the gill—rakers when it is hungry. The
Herring has a very good
“
lter,” which keeps the irritating
Copepods from the gills, but it feeds very
young
shes, especially Sand—eels- (Hardy). Forms that live —in
_
clear water have a comparatively small apparatus, those that
grub in the mud have a ne sieve.
_
And it has been pointed
,
out, especially by Schiemenzf'(;f905), that shes take to
different kinds of food accordingïto the} season and their
needs, irre‘spective of the natureThe
-
Carps
called omnivorouS'; feëding'oninsects, shellsh and "eVen plants, yet they have such an apparatus,
derived from their habit of stirring up the mud.
…
,
_
-
In the :Teleosts-the last branclal arCh, where the oral
cavity narrows to the gullet, is usually modied to serve as
a5grindig or tearing apparatus; “As shes haVe no saliVary
î
glands we can hardly"say that they maSticate their food, and
,
the teethwhich develop on the last 'brànchi'al iarchç arér—ather.
to:” be ' regar‘ded '
as :
They haVe
'
pr0bably:aiisen inthe“sanie-wayandfbecanespe01ahsedm
various” directions
thenatureofthe éfoOd*and
'
Solid-particles taken fin—to
part Of
the ‘arch —'(cerat0branêhial) is_ the onethat
frequently
bears teeth, ad in'Some{groups-the?twoïïhalves Of each side
are: fused together
foirhîa large and ‘s‘olid plate (Scornbrea
js“ocids,æLabro1ds,C1€hhds) ':i_In‘—-?Others=“the" upper par—ts
'
'
may also be fused
‘
ftOgt:therf(Scaridæ)4 5”f_ »
:
,
: -
__
—
’ *
:
bonès,like the reduction
'
:
of the
fi11sthe iPipe—shes, —hasîno =denite relation
THE BIOLOGY‘ OF FISHES
[
develop gill—r‘äkers. “ _ It may; be also that the great-difference '
f
in the size -and development of the Leptocephali comes. in
:
part from the difference in ”the amount of food they
_
get into their months,
.
-
'
«
»
The principal function of thegill—rakers is to protect
%
the delicate gill—laments—as one might-conclude from the
law of action and reaction.
It is only sècondarily that they '
are
the food.
The
“
selection
” of the latter
_
depends-on the senses, and a sh, we may be sure, doesnot
trouble to consul—t the gill—rakers when it is hungry. The
Herring has a very good
“
lter,” which keeps the irritating
Copepods from the gills, but it feeds very
young
shes, especially Sand—eels- (Hardy). Forms that live —in
_
clear water have a comparatively small apparatus, those that
grub in the mud have a ne sieve.
_
And it has been pointed
,
out, especially by Schiemenzf'(;f905), that shes take to
different kinds of food accordingïto the} season and their
needs, irre‘spective of the natureThe
-
Carps
called omnivorouS'; feëding'oninsects, shellsh and "eVen plants, yet they have such an apparatus,
derived from their habit of stirring up the mud.
…
,
_
-
In the :Teleosts-the last branclal arCh, where the oral
cavity narrows to the gullet, is usually modied to serve as
a5grindig or tearing apparatus; “As shes haVe no saliVary
î
glands we can hardly"say that they maSticate their food, and
,
the teethwhich develop on the last 'brànchi'al iarchç arér—ather.
to:” be ' regar‘ded '
as :
They haVe
'
pr0bably:aiisen inthe“sanie-wayandfbecanespe01ahsedm
various” directions
thenatureofthe éfoOd*and
'
Solid-particles taken fin—to
part Of
the ‘arch —'(cerat0branêhial) is_ the onethat
frequently
bears teeth, ad in'Some{groups-the?twoïïhalves Of each side
are: fused together
foirhîa large and ‘s‘olid plate (Scornbrea
js“ocids,æLabro1ds,C1€hhds) ':i_In‘—-?Others=“the" upper par—ts
'
'
may also be fused
‘
ftOgt:therf(Scaridæ)4 5”f_ »
:
,
: -
__
—
’ *
:
bonès,like the reduction
'
:
of the
fi11sthe iPipe—shes, —hasîno =denite relation