So))ie Ncno Primitive Theriodonts. 153 



The two form a median ridge which passes up from the middle of the 

 palate. The upper sides of the pterygoids are considerahly overlapped 

 by the palatines, so that the pterygoids appear smaller when viewed 

 from above (fig. 9) than they really are (fig. 8). 



The teeth are fairly well preserved, and owing to the manner in 

 which the snout is broken across one is enabled to observe the structure 

 and relations of the roots of the teeth. 



There are on each side 5 well-developed upper incisors. The 

 crowns are for the most part badly preserved, but each tooth, though 

 on section moderately round, has a distinct posterior edge and a less 

 marked anterior border. In the third, fourth, and fifth teeth there are 

 distinct serrations along the posterior edge. The third and fourth 

 incisors are very considerably larger and the second slightly larger 

 than the first and fifth. The fifth incisor is somewhat flatter than 

 the others. The fracture across the roots of the teeth reveals, at a 

 distance of from 18 mm. to 25 mm. above the alveolar margin, remains 

 of teeth of an earlier set in front of the roots of the first, second, and 

 third incisors. These are small portions of the roots of teeth smaller 

 than those of the succeeding set, which are not shed, but become 

 imbedded in the bone, and doubtless in course of time absorbed. 



The first of the maxillary teeth is a very large canine. Directly 

 outside of the root the fracture displays on the left side, at a distance 

 of 45 mm. from the alveolar border, the remains of the root of a small 

 canine of the earlier set, while immediately behind the large canine 

 there is seen on both sides the remains of a second large canine which 

 is being invaded by bony tissue. On the right side there remains 

 only the shell of the root, the cavity being almost filled wath spongy 

 bone. Though this large canine tooth has disappeared with the ex- 

 ception of the remains of its root, it must be a younger tooth than the 

 first molar, as the root of the first molar is partly excavated to 

 accommodate it. 



The molars number 3 on each side, and there appear to have been 

 only 3. They are simple pointed teeth, considerably flattened and 

 with serrated posterior borders. There is no indication of any succes- 

 sional molars. 



The following are some of the principal measurements : — 



Length of 5 upper incisors 63 mm. 



Length of canine about 20 



Length of 3 molars 29 



Total length of dental series 134 



Width of snout in region of canines 105 



