40 



cavities, is formed by the base of the left maxillary and the 

 base of the right intermaxillary, which both meet at the 

 summit of the head. The right intermaxillary, however, 

 does not join the occipital, but is separated from it by a thin 

 edge of the right maxillary, so that the occipital is doubled 

 in front by the base of the maxillaries alone ; in this way the 

 left intermaxillary is much shorter than the right one, and 

 mounts no higher than the wall of the left nostril, which it 

 partly forms. It is the enormous width given to this left 

 nostril that thus distorts the bones. The vomer forms with the 

 sides of the intermaxillaries a broad hollow canal, in the 

 middle of which it tapers away to a point which divides that 

 intermaxillary emargination which terminates the broad snout. 



The nostrils are pierced in the middle of the upper surface 

 of the head, not, perhaps, so obliquely as in the genus 

 Catodon ; but they are here much more unequal in size, one 

 being more than ten times the size of the other. The nasal 

 bones are in this manner thrown completely out of their 

 place. The right one is a very small triangle, at the base of 

 the ethmoidal, which forms, with the right intermaxillary, 

 the wall of the small right nostril. It also forms the lower 

 edge of the dividing ridge, and terminates abruptly and 

 perpendicularly above the base of the vomer. The left nasal 

 bone is more than two inches long, and somewhat of a 

 parallelogram in shape. With the left intermaxillary, the 

 left maxillary and the ethmoid together, it forms the wall of 

 the enormous left nostril. 



In this animal, as we have said, the two massive maxil- 

 laries touch each other behind where they are doubled by the 

 occipital, and leave no part of the frontal visible. A notion 

 of their heavy proportions may be obtained from the fact, that 

 a section of the right maxillary, taken through the right 

 nostril, perpendicular to the medial line of the head, would 

 be a triangle, having four inches and a half for its base, and 

 about one inch and a half for its height. 



Of all the orders of Mammalia the structure of the skull 

 varies most in the Pachydermata and Cetacea ; indeed, the 



