272
THE BIOLOGY
_
OF FISHES
together or one forwards, theôther backwards, as if seeking
'
'
for something—and all with the greatest serenity, remaining
quite still the while, as if it were the easiest thing in the
world (Fig. 68). We have but to practise with our arms
.
to discover that this art takes some learning.
the cartilaginous shes (Elasmobranchs) the
ventral ns, or rather their base, have been modied in the
_
males to serve as claspers. During sexual congress these
are
inserted through the cloaca of the female into the
»
oviducts and the seminal uid ows along them into the
upper parts of the latter, where impregnation of the eggs
takes place. — In some of the .bony shes or Teleosts it is '
the anal n that is so modied-. This is the case especially
'
among the viviparous shes of the Cyprinodont family, -
where in some forms the anal n serves no other purpose
but as a kind of "intronuttent organ (Fig. 73). The great
.
of shes do not haVethese adaptations, So that it
‘
is clearly impossible to regard them as necessary or indis—pensable for the preservation of any
Since they
"
only occur in the males their origin and development have
,
to be associated with the nature of the latter.
In other cases,
especiallyamong the Cottoids, Lumpsuckèrs, Cling-shes,
'GObieë,‘ and other shes that live'àmongst the
in”
,
'
shallow water, the
_
uriogenitéæl
'swells Out into a:
-
large
thebreeding
used as
;
an intromittent‘organ in the
(someBlenmes ,
Emb10toadsetc)Butm the nonvmparousshes
: whtquywdlpdthggfd
afterextruswnHere asw1th0therstructures theongm
*
from 1tslateruse
:.î'
.
_.
_
In:thè sedentaryformsÿïorfth0seÊ:that do- not move about
to any great
other structures of interest are
; ,
‘,d6Velopedf’afç
season.— In some of the Pipe—'
_
“shÇS (Syngnathidæ)læèral folds of skin expand =outWards
{under
tofmeet= andform a Closed pouch, in which
‘
*‘—the_malèsieçCei—v‘e theeggs
the young, ;
Ïj:Ï p__ingëîoêjDuncker
become
the skin of the
THE BIOLOGY
_
OF FISHES
together or one forwards, theôther backwards, as if seeking
'
'
for something—and all with the greatest serenity, remaining
quite still the while, as if it were the easiest thing in the
world (Fig. 68). We have but to practise with our arms
.
to discover that this art takes some learning.
the cartilaginous shes (Elasmobranchs) the
ventral ns, or rather their base, have been modied in the
_
males to serve as claspers. During sexual congress these
are
inserted through the cloaca of the female into the
»
oviducts and the seminal uid ows along them into the
upper parts of the latter, where impregnation of the eggs
takes place. — In some of the .bony shes or Teleosts it is '
the anal n that is so modied-. This is the case especially
'
among the viviparous shes of the Cyprinodont family, -
where in some forms the anal n serves no other purpose
but as a kind of "intronuttent organ (Fig. 73). The great
.
of shes do not haVethese adaptations, So that it
‘
is clearly impossible to regard them as necessary or indis—pensable for the preservation of any
Since they
"
only occur in the males their origin and development have
,
to be associated with the nature of the latter.
In other cases,
especiallyamong the Cottoids, Lumpsuckèrs, Cling-shes,
'GObieë,‘ and other shes that live'àmongst the
in”
,
'
shallow water, the
_
uriogenitéæl
'swells Out into a:
-
large
thebreeding
used as
;
an intromittent‘organ in the
(someBlenmes ,
Emb10toadsetc)Butm the nonvmparousshes
: whtquywdlpdthggfd
afterextruswnHere asw1th0therstructures theongm
*
from 1tslateruse
:.î'
.
_.
_
In:thè sedentaryformsÿïorfth0seÊ:that do- not move about
to any great
other structures of interest are
; ,
‘,d6Velopedf’afç
season.— In some of the Pipe—'
_
“shÇS (Syngnathidæ)læèral folds of skin expand =outWards
{under
tofmeet= andform a Closed pouch, in which
‘
*‘—the_malèsieçCei—v‘e theeggs
the young, ;
Ïj:Ï p__ingëîoêjDuncker
become
the skin of the