116
j
,
THE;
OF FISHES
ÿÿ_i_f'bùt_;many other ,shes are just as
“
at
” without becoming
asymmetrical in the head region.
Some approach very near
to this condition, but so long as the abdominal organs
remain free, the asÿmmetry of the body does not make the
,
skull asymmetricai.
' ;
,
In— the other group of Flat-shes (Symphurus) the body
is not at ; it is rather rounded to begin with, such aswe
nd in the BlennieS and elongated Gadoids. The caudal
region is comparatively long and there is a large air—bladder,
,
as is,—sooften the_casé, on the left side.
asymmetry
13 thus Very markedin sections (Fig. 30, 2) and one can see
that such a—b0dy must roll and twist when moving through
‘
the Water.
rolling has a bias to the left side
aèÇting{the tissues to suchan extent, that the left ventral_
Whilst_the right ventral is twiSted
,
'
doWn;td the middle line. 'The pectoral ns are large and
,
stages.
In these forms there
;
amount; of lymph0id— tissue, under"the skin
"
'
and inside andoutside the
showing the presence of , .
‘
,‘frictionbetWeen the_dierent par—ts.
=
'—Hef6 the 2ÏSymmetry developS mainly from-the ;Ÿiolent ,
_
the“ head from side to side. '_—VVith the bias}of“
-the body theÏmouthpa—rts: are
the (left; the tissues ..
ithe right side of. the
new
,*î:';fÊ_.
,
Connections, are formed ,_betw€enÏ the pmmamllaryabove and
ÎdentàW'belowz »
_
dv1pf…d ymnty …… fm With
,
anabdonnnalrod1tcompressesbeththeabdormnal organs
î‘Î andthemrbladderThef0owmgchanges are rapidly
"
gnthugh(Fg33) {Th aaa—bladder suddenly
dlsappeafs,thesh0defg“dle is. Puued VÏÔIŒÜY baCkf ?
:
upWards ; the from“ end,
;Îaÿlg
Ofthe Spoùt
,is ,. also bent up and to the right.
'
these changes;
'
the .peototal,ns
“
-‘Ïîth.@ëtightçzély6:dçisappearsÏfrom the ght-side and;è—is squiœædî’ f
:* ' ,
to; the Other
the ;—