SKELETON OF CETACEA. 421 



nasal meatus : it again slightly expands, and afterwards is con- 

 tinued, gradually decreasing, to near the anterior end of the pre- 

 maxillaries : it is canaliculate above, and occupied by cartilage 

 continued from the coalesced prefrontals. There is no trace of 

 nasal bones. The bone, formed by the coalesced prefrontals, 

 penetrates the posterior part of the groove of the vomer, above 

 which it expands, unequally, into an obtuse prominence rising 

 and inclining to the left side : it is grooved on both sides, and 

 forms the septum of the vertical nasal passage : it is not com- 

 l)licated with turbinal or rliinal capsules, as in the so-called 

 ' ethmoid ' of other Mammals. The palatine and pterygoid bones 

 articulate mth the sides of the expanded base of the vomer : the 

 margins of the canal excavated in the upper surface of the rostral 

 production of the vomer are overlapped by the premaxillaries. 



The palatal is a small, triangular bone, thickest anteriorly, 

 thin, produced and bent posteriorly and above : it commences 

 here by its attachment to the anterior and outer angle of the 

 vomer, bends forward, downward, and inward to circumscribe the 

 nasal meatus, and receives in a groove on its upper and anterior 

 border the palatine prominence of the upper maxillary bone. 

 The whole posterior border of the palatine fits into a groove of 

 the contiguous border of the pterygoid. The pterygoid, Avhich is 

 double the size of the palatine, extends backward to the basi- 

 occipital, articulating in its progress by its expanded upper border 

 with the pre-, basi- and ali-sphenoids : from this border the bone 

 descends, arching inward toward its fellow, which it joins along 

 the anterior half of its extent : the remaining free border is divided 

 from this by a deep notch, and circumscribes the large posterior 

 bony aperture of the nostril. 



The maxillary expands from its palatine prominence — the 

 essential point of its suspension — backward, outward, but chiefly 

 forward, where it gradually diminishes to an obtuse point. It 

 contracts a union posteriorly with the orbitosphenoid and ali- 

 sphenoid, and very extensively with the frontal. The nasal 

 process of the maxillary is traversed by a large vertical canal. 

 The premaxillaries are applied against the whole inner surface of 

 the maxillaries between them and the vomer. The right extends 

 much farther back than the left. The capacious basin on the 

 upper surface of the skull, which lodges the valuable product 

 called ' spermaceti,' is formed by the expanded and concave nasal 

 processes of the premaxillaries and maxillaries, which overlap the 

 frontals : a stout ridge divides the inner concave from the outer 

 sloping surface of this part of the maxillary. The malar bone is 



