2
F. W. MUNZ
&epchoOriM
lymph space
V F d
susmnsorv I I I \
Fig. 1. Diagrammatic vertical section of a typical teleost eye. Not all structures
shown are present in every teleost eye; e.g., hyaloid vessels are not present in
conjunction with a falciform process. From Walls ( 1942).
of six oculomotor muscles. Except in cyclostomes, in which it is fibrous,
the sclera is usually reinforced with cartilage. This is often calcified in
elasmobranchs; teleosts frequently have one or two scleral ossicles in addition to cartilaginous support. Little refraction occurs at the corneal surface, for its refractive index approximately equals that of water. In air,
however, the fish eye is myopic because of the added refraction. Baylor
(1967b) has shown that in flying fish the corneal surface is pyramidal,
with the lower third covered by a flat face. When the flying fish is airborne, its downward vision should be relatively undistorted. Many fastswimming teleosts have additional streamlining and protective structures,
the transparent “adipose eyelids.” These vertical folds, which are really
adipose in Mugil, but not in clupeoids or scombroids, overlie the cornea
in various configurations. Many sharks have mobile eyelids; in some
species there is an active nictitating membrane.
F. W. MUNZ
&epchoOriM
lymph space
V F d
susmnsorv I I I \
Fig. 1. Diagrammatic vertical section of a typical teleost eye. Not all structures
shown are present in every teleost eye; e.g., hyaloid vessels are not present in
conjunction with a falciform process. From Walls ( 1942).
of six oculomotor muscles. Except in cyclostomes, in which it is fibrous,
the sclera is usually reinforced with cartilage. This is often calcified in
elasmobranchs; teleosts frequently have one or two scleral ossicles in addition to cartilaginous support. Little refraction occurs at the corneal surface, for its refractive index approximately equals that of water. In air,
however, the fish eye is myopic because of the added refraction. Baylor
(1967b) has shown that in flying fish the corneal surface is pyramidal,
with the lower third covered by a flat face. When the flying fish is airborne, its downward vision should be relatively undistorted. Many fastswimming teleosts have additional streamlining and protective structures,
the transparent “adipose eyelids.” These vertical folds, which are really
adipose in Mugil, but not in clupeoids or scombroids, overlie the cornea
in various configurations. Many sharks have mobile eyelids; in some
species there is an active nictitating membrane.