ECONOMY OF THE BODY—II
163
must be different from ours. '
'
It is perhaps little more than
a vague discrimination of light and Shade, With a 'V‘ary‘ing
perceptiozof colour.
—
"
—'
—
,
'_rIn some shes, however, the 'forrhati0n ofäfthe
,
'
‘
brings the two eyes closer together and the'fdeVelOpiént
[
'
of a *synovial bùs1'sa or “r‘ecessus‘orbitalis ’,"
_
ball aids in its prbtrùsion and rotation, as .ifFlatzshes;
,
VVehave
,
but to Contrast the behaviour of 'a
;
.
Plaice in aàquarium to see what a differencethiS makes;
.
'
The eyes of the former have a xed stare, those of- -the'
…_'
latter can be cocked up and quickly ‘rotated, as ifthe sh“
"
were alert and constantly on the watch. VVh'en
'
,
tion-of the skull gives the eyes a common eld of yision
"
,
fr‘ontor above, the precision of the image and perception
'
,
of distance are greatly intensied. 'These cases are
rare,but— we may Well beli€vethat such an enhanCecl
_
,
_of Vision “is of assistance to Periophthalmus when it:wa£nderS
'
bushes (cf. gure on
_
”:'Ï
stalked " or “'telescopic
eyes Of
also serye for binoc1ilar;vision. They:are
corneà in front and
of rays on a dèniœ SpOt ;
Ï :?
Îbut1tisall very i‘mysteri‘ous ,“ since there is
where
' .
live.- And theëprOtrusion'of the eyesmaybeln
great part articial. As mentioned previous1y, when the
.
'
-
eggs of Trachypterus are brought upi'to
of the embryo are distinctly
,
…
sink back to a normal condition afterïtwoorifthree”days when
j
the internal pressure has
ëXË€TÎIQÏÉ Î11
iÏ
This may, in part,
of the Stylophthalmus obtained—
of the Indian Ocean(F1g42),andtheyoungformsOfdeêpsea species when broughtth 'thefsurfa0e
=A great ïdeäli=—hàS-*' bëenï‘Wi“ÿîttéabouttheextraordmŒY,Ï
eyes,
th1psunddpttt0the;:ä=a