212 THE VOYAGE OF H.M.S. CHALLENGER. 



The Levator labii superioris et aim nasi in Phoca vitulina is a rectangular muscle. It arises 

 from the dorsal surface of the frontal bone which lies between the orbits, the same surface of 

 the nasal bone, and the superior maxilla, nearly reaching the nasal orifice anteriorly. The fibres 

 proceed downwards and outwards, and are inserted into the muzzle from the nose to near the 

 angle of the mouth. It is supplied by the facial nerve. 



The Muscles of the Eyelids. — The Orbicularis palpebrarum in Phoca vitulina arises from the tendo- 

 palpebrarum inferior to the pulley for the superior oblique, from the palpebral ligament superior 

 to it, from the frontal bone, and from the superior maxilla. The orbicular portion blends with 

 the corrugator supercilii and the occipito-frontalis fascia, and is attached to the superior maxilla, 

 to the ligament completing the orbit, and to the malar bone. The palpebral portion is feeble and is 

 attached to the malar bone. 



The Tendo-palpebrarum arises from the nasal process of the superior maxilla, and ends in the 

 orbicularis palpebrarum, lying along the inferior surface of the tendon of the superior oblique. 



The Superior palpebral ligament goes from the superior maxilla above the tendon of the superior 

 oblique to the orbicularis palpebrarum. 



The Corrugator supercilii arises from the frontal bone and is inserted into the under surface of 

 the orbicularis and the occipito-frontabs. 



The Tensor tarsi arises from the orbital surfaces of the frontal and superior maxilla three-fourths 

 of an inch below the nasal process of the latter. It ascends and is inserted into the tendo-palpe- 

 brarum at the junction of the lid and the tendo-palpebrarum. It blends with the orbicularis. 



The Levator palpebrm superioris in Phoca vitulina arises from the upper margin of the optic 

 foramen external to the superior oblique. It passes forwards, expands, and is inserted into the 

 upper eyebd. It is supplied by the 3rd nerve. 



The Muscles of the Orbit} — Besides the four recti and the two oblique muscles, there are two 

 retractors and two depressors of the third eyebd. 



The Superior, Inferior, External, and Internal recti muscles resemble the corresponding human 

 muscles. 



The Superior oblique arises from the inner, and sUghtly from the upper, surface of the optic 

 foramen. It passes forwards along the inner wall of the orbit beneath the bgament for the upper 

 eyelid through the pulley attached to the superior maxilla, and goes outwards to the eyelid and is 

 inserted into the eyeball on the inner side of the insertion of the superior rectus. The tendon after 

 passing through the pulley lies between the tendo-palpebrarum and the superior palpebral bgament, 

 and pierces the upper eyelid to gain its attachment. The pulley is attached to the superior 

 maxilla upon the margin of the orbit close to the articulation with the nasal process of the 

 frontal bone, posterior to the nasal process of the superior maxilla. It is supplied by the 4th nerve. 



The Inferior oblique arises from the orbital surface of the superior maxilla to the inner side of 

 the inferior orbital foramen. It goes upwards and outwards round the eyeball, and is inserted into 

 it inferior to the external rectus attachment. It is supplied by the 3rd nerve. 



The Superior external and Superior internal retractor muscles arise from the outer side of the 

 optic foramen, run along the optic nerve to the eyeball, and are inserted on the corresponding sides 

 of the sclerotic beside the optic nerve. 



The Deprrcssors of the third eyelid arise together from below the optic foramen, widen out as 

 1 Rosenthal's description of the muscles of the orbit differs considerably from mine. 



