522 CETACEA. 



plates, directly above the nasal septum, are separated from each other by a rough 

 groove continuous with the lower roughened surface of the mesethmoid ridge, to 

 which the cartilage of that bone is attached and which is prolonged forwards 

 chiefly between the premaxillse to the extremity of the snout. The nasal plate 

 is thin and slightly expanded from above downwards, ending below in a free 

 sharp margin. A deep triangular anterior longitudinal notch separates the wings 

 from the vertical plates, but both are closely applied to the premaxillse and 

 maxillae. At the upper margin of the wings, anterior to the nasal septum, they 

 are separated by an oval nodose rough surface, which is prolonged downwards 

 and forwards between the free extremities of the wings, and to it the mesethmoid 

 cartilage is also attached. 



Palatine (PL XL, fig. 12, and fig. 17 w).— The peculiar position of this bone 

 in Flatanista was first pointed out by Eschricht. It appears in the anterior and 

 outer walls of the nasal cavities, and is placed so high in them that its upper 

 extremity rises above the low anterior border of the external nares in the dried 

 skuU, the lower half of its nasal surface forming the anterior, and its upper half 

 the external wall of the nasal cavity. The former completes the canal, but is seen 

 with difficulty, owing to the backward projection of the pterygoids. When the 

 maxilla is separated from the skull, the palatal is seen to invest the greater part 

 of its posterior and external borders, below the frontal plate and the inferior 

 border of the vomeric crest of the maxilla. It is nearly vertical, but has a 

 slightly downward and forward course. Viewed from the outer side, it is seen 

 to form the posterior boundary of a large round foramen in the maxilla, the 

 inward and forward continuation of the pterygo-maxillary fissure. The lower 

 border of this foramen is defined by a strong longitudinal lamellar process, the 

 backward continuation of the external plate of the maxilla, which also forms 

 the lower outer wall of the pterygo-maxillary fissure externally. This process ter- 

 minates abruptly on a line with the posterior margin of the large foramen, and 

 its root is so deeply grooved and so firmly embraced by a notch about the middle of 

 the vertical height of the palatal (the two are clasped together like a hook and eye), 

 that they can only be separated by fracture. The notch divides the palatal into two 

 external surfaces, a superior and inferior ; these form a very obtuse angle with 

 each other, the former being directed upwards and inwards and the latter downwards 

 and inwards, due to the spirally curved character of the nasal surface. The upper 

 surface is also slightly bent from before backwards and inwards, and the inferior por- 

 tion, which is concave from without inwards, has its posterior margin a little out- 

 wardly curved. The former has its upper extremity abruptly truncated and somewhat 

 concave where it embraces the inferior extremity of the external surface of the 

 frontal plate of the maxilla. The inferior portion has a pointed extremity which 

 reaches close to the lower margin of the posterior angle of the vomerine crest of the 

 maxilla, so that it is only excluded from appearing on the middle of the palatine 

 surface by a few lines, and is directly below the pterygo-maxillary fissure. The 

 whole of the lower and one-half of the superior surface are completely hidden by 



