129 



that there are three nutrient canals at the tip of the jaw on each side, probably 

 indicating the normal number of teeth. In Figure 2, which shows the upper 

 sui-face of the jaw, there is only one socket on each side [a and a'), which held the 

 tooth figured of natural size (4a and 4b.) The upper conical part of this tooth 

 has a polished surface, but never proti-udes through the gum. 



This is well shown in Figures 5 a and 5 b, the first of which shows the left 

 side of the top of the jaw, with the integuments still in place, the position of 

 the tooth being only revealed by a slight elevation without any aperture. 

 The second shows the opposite side of the jaw with the integuments 

 removed, and the tooth which came away imbedded in a fold of the gum, 

 dissected out and rejplaced in the socket. 



Plate XYI. gives the superior, inferior, and profile views of the skull of 

 the third specimen referred to by Dr. Knox ; the dimensions of which are as 

 follow : — 



Length of head . ■. 



„ nose 



„ denial groove 



,, lower jaw . 



Width of notch » 



,, at orbits 



,, blow-holes . 



,, nose . 



Height of occiput 



59-5 

 31-0 

 .15-0 

 43-0 

 14-5 

 24-5 

 7-0 

 5-0 

 19-5 



Plate XVII. gives the corresponding view of the lower jaw (Figures 

 1 and 2), and also the tooth (Figures 3 a and 3 b), both in side view and in 

 section, showing the internal structure. The form of the tooth is more turned 

 than in the other specimen, but the variety is probably due to age. 



The preparation of the nose (Figures 4 a and 4 b), show that notwithstanding 

 this is a full-sized animal, the tooth is still sheathed in the gum, being 

 imbedded in a tough cartilaginous sac, which adheres loosely in the socket of 

 the jaw, and is moved by a series of muscular bundles that elevate and 

 depress it. 



The accompanying drawings (Plate XIII., figs. 2, 3 and 4) give the anterior 

 view of the atlas and six combined cervical vertebra, also the scapula and 

 anterior limb. 



