110
._
THE BIOLOGY OF FISHES
'
of the larval Hippocampus (1882), and in the Pipe—sher;
:
represented here (Fig. 27 e 5, 6, 7). ,
.
'
The eect of this breakdown of the palatinearch is to
set free the ethmoid plate of the skull from any restraining
inuence on its growth forWards.
He_nce arises the
beginning. of the long snout
characteristic of the Flute—
,
months and Pipe-shes. The mouth is now practically '
—
closed so far as the _originalopening apparatus is concerned.
..
Meantime, ossication has begun in the head region, and
“
this with the longer snout gives the head a preponderance
over the tail region. The end of the not0chord bends up
in the usual way and a caudal n is formed.
In F istularia,
h0weve‘i*, this is not sufficient to maintain the balance. The
_
! Ï
snout continues—to grow forWard and the middle rays of the
_
:
caudal n grow backwards until they become a long append—
'
'
age, almost one—fth of the total length, characteristic of the
adult Flutemouth.
In other Pipe—shes the snout does not
:
gr0w ont so far,- and there are several stages in the develop—
'
ment of the caudal region ;" there may be a tail n, but the
preponderance
the tail becomes more marked, no n
_,
develops and the tail curls downwards, as in Hippocampus.
î
,.
The closure of the month brings with it the eleVation of
_
'
th€hyoid arch and the basibranchials ; this has the eect of
’
:
disorganising- the
.
breathing apparatus. In Fistularia the
gills are able to develop, but are compressed and Small,
…
In the Pipe—shes the hyoid, arch is doubled up, due ’ç0îhé
greater .retraction of the:
arch (Fig. 27 :. 5, 7);
and the. gills;hä%little chance of deVeloping ; only a few
‘
Î
tufts'are able
to grow (LophobranChiaæ condition).
_
n€äW mouth dÇV610ps just “as in_ the .Clupeids. ., The
maxillary
head to the palatine, carried
'f0rWard by the ethmoid plate, andhasfthe‘ expanded jugal
,
fP0ftiQ.n » characteristic of the
Normally . this
jugal bone is the basefor the inSettioïi,,of’the closing‘ müSclejs
of the mouth,=which arise from the suspensorium and Skull
behindthe eye—ball. '.
)
_—_‘—17_£lÿ$ÇkStput
other muscle bres appear
"
eye—ball which. come to operate on the jngal.
._
THE BIOLOGY OF FISHES
'
of the larval Hippocampus (1882), and in the Pipe—sher;
:
represented here (Fig. 27 e 5, 6, 7). ,
.
'
The eect of this breakdown of the palatinearch is to
set free the ethmoid plate of the skull from any restraining
inuence on its growth forWards.
He_nce arises the
beginning. of the long snout
characteristic of the Flute—
,
months and Pipe-shes. The mouth is now practically '
—
closed so far as the _originalopening apparatus is concerned.
..
Meantime, ossication has begun in the head region, and
“
this with the longer snout gives the head a preponderance
over the tail region. The end of the not0chord bends up
in the usual way and a caudal n is formed.
In F istularia,
h0weve‘i*, this is not sufficient to maintain the balance. The
_
! Ï
snout continues—to grow forWard and the middle rays of the
_
:
caudal n grow backwards until they become a long append—
'
'
age, almost one—fth of the total length, characteristic of the
adult Flutemouth.
In other Pipe—shes the snout does not
:
gr0w ont so far,- and there are several stages in the develop—
'
ment of the caudal region ;" there may be a tail n, but the
preponderance
the tail becomes more marked, no n
_,
develops and the tail curls downwards, as in Hippocampus.
î
,.
The closure of the month brings with it the eleVation of
_
'
th€hyoid arch and the basibranchials ; this has the eect of
’
:
disorganising- the
.
breathing apparatus. In Fistularia the
gills are able to develop, but are compressed and Small,
…
In the Pipe—shes the hyoid, arch is doubled up, due ’ç0îhé
greater .retraction of the:
arch (Fig. 27 :. 5, 7);
and the. gills;hä%little chance of deVeloping ; only a few
‘
Î
tufts'are able
to grow (LophobranChiaæ condition).
_
n€äW mouth dÇV610ps just “as in_ the .Clupeids. ., The
maxillary
head to the palatine, carried
'f0rWard by the ethmoid plate, andhasfthe‘ expanded jugal
,
fP0ftiQ.n » characteristic of the
Normally . this
jugal bone is the basefor the inSettioïi,,of’the closing‘ müSclejs
of the mouth,=which arise from the suspensorium and Skull
behindthe eye—ball. '.
)
_—_‘—17_£lÿ$ÇkStput
other muscle bres appear
"
eye—ball which. come to operate on the jngal.