DE. J. MUEIE OX THE ANATOMY OF THE SEA-LION. 503 



scooped; the jugal extension is a tapering rod. The jugal bone is not very stout, 

 though at its middle high, in an upward angle. Bifurcate in front, it forms a firm 

 union with the maxillary retrovert process. 



A considerable part of the face or muzzle is taken up by the intermaxillary, so that, 

 excepting the canine eminence, each maxillary chiefly outflanks the cheeks only. The 

 basal segment of the maxilla rises high, is flatly convex, and of fair breadth. Behind, 

 the canine eminence is deeply and widely grooved, where lie the thick infraorbital 

 nerves and vessels. There is a small but distinct antorbital prominence. The max- 

 illary orbital surface is moderate, and tolerably vertically concave forwards. The pala- 

 ' tine region of the maxillary is of fair breadth, and terminates in a long spear-shaped 

 palatine strip guarding the palatine plates of the palate-bones almost to the posterior 

 nares. Each premaxilla is flattish and truncate anteriorly towards the alveolus, and 

 rises therefrom in a narrowing outspread arch enclosing the anterior nares. The narial 

 orifice in front is heart-shaped, H inch deep and 1£ inch at its upper widest part. The 

 upward strip of the premaxilla is inserted between the nasal and maxillary bone as a 

 narrow wedge. The large turbinals are much convoluted and almost occlude the narial 

 passages, but within the maxillary area. The vomer is in great part hidden, and has 

 no connexion with the horizontal palatine plates. 



The nasals in some respects are like the premaxillaries in being wide below and 

 narrow above. Each is 1-8 inch long, and about half an inch at widest or below. They 

 are suturally connected nearly their whole length, posteriorly divaricating ; the forks 

 fit into the frontal. One half of their outer margin abuts against the maxilla, the 

 remainder in front lies upon the premaxilla. 



The frontal bones are peculiar from their length, postorbital processes, and great 

 constriction behind these. Their upper surface is smooth and flat anteriorly, and widely 

 convexly arched behind. Their orbital surfaces are of great length, considerably scooped 

 out, and but moderately deep, a long vacuity existing between them and the maxillo- 

 palatines. 



The palatine plates of the palate-bones, as has been noticed by many authors, are un- 

 commonly long and broad — in this case fully 2J inches in antero-posterior, and above 

 H inch in transverse diameter. Their hinder margins are transversely abrupt, and the 

 posterior nares constricted. Laterally and exteriorly the palatine walls reach high, and 

 present a great pterygo-sphenoidal surface. 



The basisphenoid is short, but wide. The pterygoid processes stout, and with a sharp 

 recurved hamular process. The alisphenoids are fair-sized, distinguished by a square 

 boss where they join the postfrontals. There seems, however, to be a large orbital 

 plate : but this is mainly composed of the postfrontal ; for the orbito-sphenoidal area 

 is very narrow and small. 



c. The Mandible. — The two halves of the inferior maxilla have no bony anchylosis, but 

 are united to each other by synchondrosis. This separation is not merely the result of 



4a2 



