. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. An external View of the Eye, Eyelids, Muscles, Sfc. of a Crocodile. {After John Hunter?) a, the external surface of the upper eyelid; b, the external surface of the under eyelid; c, points to the edge of both eyelids; d, the inner angle or canthus of both eyelids; e e, the internal surface of the eye- lids covered by the tunica conjunctiva; /, point, to the two puncta lachrymalia on the inside of the under eyelid; g, the external surface of the third eyelid, or membrana nictitans; h, the loose or free edge of the same ;
. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. An external View of the Eye, Eyelids, Muscles, Sfc. of a Crocodile. {After John Hunter?) a, the external surface of the upper eyelid; b, the external surface of the under eyelid; c, points to the edge of both eyelids; d, the inner angle or canthus of both eyelids; e e, the internal surface of the eye- lids covered by the tunica conjunctiva; /, point, to the two puncta lachrymalia on the inside of the under eyelid; g, the external surface of the third eyelid, or membrana nictitans; h, the loose or free edge of the same ; 1i, the opening of the duct of the lachrymal gland (glandula Harderii) upon the inner surface of the nictitating membrane ; this surface has been raised from the cornea, to which it naturally lies contiguous; Z, the muscle which expands the membrana nictitans, and draws it over the ball of the eye. This is the only muscle which is subservient to the movements of the nictitating membrane; it is analogous to the pyra- midalis of birds, the quadratus muscles and its sheath being wanting in reptiles ; m, the levator muscle of the upper eyelid; n, the portion of the above muscle lost in the tunica conjunctiva; o, the depressor muscle of the under eyelid; p, the rectus superior, or attollens oculi; q, the rectus in- ferior, or deprimens oculi; r, the rectus externus, or abducens oculi; s, the obliquus inferior: only a small portion of it is here seen ; t, the cornea; u u, the globe of the eye behind the cornea; v, the optic nerve; x, insertion of the choroid muscle, which consists of four distinct portions surrounding the optic nerve. able points at both extremities. The quadratus muscle, which in birds forms a loop for the passage of the tendon of the nictitator, does not exist in the reptilia. There is a gland especially appropriated to facilitate the move- ments of the nictitating membrane by its secre- tion, which escapes through a duct opening upon its inner surface. This gland
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