ÊAD'A‘PTATIONî
-
’
J Ï
'28i
-
'
can see from 'variôus ”things that they have arisen from the
irritation caused by foreign bodies on ”the delicate liningÏ
membrane of the arches and they
number With
‘
the growth. Where the sh lives mostly on Œhérsh or the
’
hard—shelled Mollusca the ràkers are;solid
hard; like
tubercles, as in the
itÏfeeds
mainly on ._plankton———the 0ating' or 'i sWimmin-g
Î Œgahi$ms
of a smaller lîind4—the fakers are
in,
[
the “Herring or Shad (Fig. 72, 2)»: -In both cases the ral;e1‘s
may be branched and s'o'der‘1Selypacked on the
-
as
to 'fornr a perfect sieye
The -mOS”t…peract
example 6f’a sieve is
in-thefBaiskii1g- Shark;a large
'
sh 'that lives near the s‘uifacead feeds mainly on the siall —
,
sheSar—id marine‘Inyèebra‘c‘esk‘,“’.? =
ï
;;';
Ï
,
'
»'
'
'
z
-
1,a1
:
.;
FïG7z—Glsandglrakers(FromZander)
—
'.
::
‘hyal(togu€),oe,œsgph2gus
—,
'
'
…
,
thatthemode
'
;
_
'
of life ;of thefaduj
apparatus. It is the last
the permanentstrucü1restobe
:
developed in the
devdbp‘1‘entiS; connected
With the—conditions in the early stages,: duringthe rst—few
'
:
months of the larval
=Several shes, including the’Eel, '
;
haveno gill—rakers‘. One may infer from this that the young ,
.
their three years’ sojourn in the Northf
'
Àt1æfç, rdpÎÎth encounter irritating organisms «or«dQ net
the ,mouth._, _Hence… the $C)—called f "
'
_
are:aconspicuoùs
"
deep=sea forms
”as 'a _ltering2
_
are
“
fdriëd on the"edgeiof
:
probably fnot =ältdgether =usefulOtherdeep-seashæ,
,_
,