XII.] CETACEA. 1S9 



///) being directed somewhat backwards. They are com- 

 pressed before backwards above, but wider and more round 

 below. The nasal bones [Na)^ instead of being lamelliform, 

 and roofing over the nasal passages, are reduced to nodular 

 masses, lying in depressions in the frontals, but forming as 

 usual the hinder boundary of the anterior narial openings. 



In front of these openings, the face stretches out into 

 an elongated, depressed, pointed beak, or rostrum, formed 

 by the premaxillae and maxill?e surrounding the vomer and 

 mesethmoid cartilage. The premaxillse send prolongations 

 upwards to form the lateral boundaries of the narial orifice, 

 and it is remarkable that these are not quite symmetrical, 

 that of the left side being the shortest. The orifice itself, 

 moreover, is rather inclined towards the left. Between the 

 antorbital process of the maxilla and its rostral prolongation 

 is a deep notch, the "antorbital notch." The upper surface 

 of the face, near this notch, has several very large foramina 

 for the transmission of branches of the fifth nerve. 



The elongated, pointed, and convex palate is formed 

 chiefly by the maxillae (Fig. 62, AIx), the premaxillas {PMx) 

 only appearing for a short space near the apex. Behind 

 the maxillae, the palatines {Fi) are somewhat wide laterally, 

 but towards the middle line form an exceedingly narrow 

 strip, inserted between the maxillae and the pterygoids (Fi); 

 the latter are greatly developed; besides forming the outer 

 wall of the posterior nares, each sends a lamella inwa.T-ds, 

 which nearly (in most Dolphins, completely) meets its fellow 

 in the middle line, and so prolongs the bony palate back- 

 wards. This process, moreover, is reflected outwards again 

 from its inner or lower edge, and, joining with a projecting 

 plate from the palatine, encloses a large cavity, open only 

 behind, which contains the post-palatine air sinus. The 

 vomer ( Vo) is of great size, extends forwards nearly to the 



