REPORT ON THE SEALS. 213 



they near the inferior margin of the third eyelid, pass on each side of the Harderian gland, 

 and are lost in the substance of this lid. The cartilage in this eyelid is strongest in the centre, 

 where it forms a strong vertical rod. The eyeball is surrounded by a fibrous case which lines 

 the wall of the orbit, forming the periosteum, and on the outer side, where there is no osseous 

 protection, the periosteum is continuous with the fibrous case along the sharp edge of the 

 pterygoid and palate bones inferiorly, and the nasal and frontal supeiiorly. 



The Orbital ligament completes the break in the circumference of the orbit. It is attached to the 

 malar and temporal bones at their zygomatic articulation, and to the frontal bone above the orbit 



The Muscles of the Mouth. — The Orbicularis oris in Phoca vitulina surrounds the mouth, and, 

 where it passes from jaw to jaw, is indistinct. It arises from the under surface of the inferior 

 maxilla by fine fasciculi as far back as the 4th molar tooth. The fibres ascend round the angle of 

 the mouth, and are inserted into the superior maxilla from the 4th molar to the articulation of the 

 premaxilla ; some of the fasciculi next the symphysis and the premaxilla circle round the mouth. 

 It is supplied by the facial nerve. 



The Levator labii supcrioris proprius arises from the superior maxilla, forming the margin of the 

 orbit, and is inserted into the upper lip. It is supplied by the facial nerve. 



The Buccinator muscle in Phoca vitulina is very small and composed of feeble muscular fibres. 

 It arises from the superior maxilla from a line extending from the last molar backwards along the 

 edge of the palate bone to midway between the root of the zygoma and the hamular process of the 

 pterygoid, from the inferior maxilla, from a linear origin from above the inferior dental foramen 

 to the last molar, and from the pterygo-maxillary ligament. It is inserted into the orbicularis 

 oris. It is supplied by the facial and the 5th nerves. 



The Levator anguli oris in Phoca vitulina, arises from the junction of the nasal bone with the 

 premaxilla, and from the protuberance of the superior maxilla. It is inserted into the canine fossa 

 and into the skin of the mouth anteriorly beneath the infraorbital nerve and the dilator nasi. It 

 is supplied by the facial nerve. 



The Muscles of Mastication. 



The Masscter in Phoca vitulina and in Arctoccphalus arises from the whole of the zygomatic arch, 

 and is inserted into the fossa of the lower jaw below the coronoid root to where the alveolar 

 margin commences. It is supplied by the inferior maxillary nerve. 



In Otaria there are two layers of fibres, a superficial and a deep set. 



The Temporal muscle in Phoca vitulina and in Arctocephalus covers the side of the cranium, below 

 the temporal ridge which traverses the parietal bone, running obliquely forwards from the middle of 

 the occipital ridge to the root of the nasal process of the frontal bone. It lies between this line 

 superiorly and the zygomatic arch inferiorly, and arises from the lower half of the parietal, from the 

 squamous surface of the temporal bone, from the outer surface of the frontal inferior to the 

 oblique line, from the outer half of the anterior orbital surface of the same, and from the superior 

 tip of the alisphenoid. It converges and is inserted into the outer border, anterior border, and 

 internal surface of the coronoid process of the lower jaw, coveiing the internal surface above a line 

 drawn from the condyle to 1 inch behind the last molar. It is supplied by the inferior 

 maxillary nerve. 



