150 Annals of the SoiitJi African. Museum. 



premaxillary supports six incisors, but they are so badly preserved 

 that it is impossible to give any description of their characters. So 

 far as preserved each tooth is practically round without serrations. 

 The first tw^o teeth are moderately small ; the next three much 

 larger, and the sixth incisor very small. The maxillary bone 

 gives support to ten teeth (possibly eleven), but it is a little difficult 

 to classify them in terms of the mammalian nomenclature. Near 

 the front of the bone is a large tooth that might very readily be 

 looked upon as the canine, but this is not the most anterior tooth of 

 the maxillary. In front of it is a very minute pointed tooth, fairly 

 well preserved, on both sides of the skull. It is difficult to believe 

 that this minute tooth is the homologue of the mammalian canine 

 and the large tooth behind it the homologue of the mammalian first 

 premolar, though this is undoubtedly possible ; and as it seems much 

 more probable that the large tooth is the homologue of the mam- 

 malian canine, the small tooth may be referred to as the first canine, 

 and the large one as the second canine. Only the bases of the two 

 canines are preserved, but it seems not improbable that the posterior 

 margin of the large canine at least was serrated. Behind the second 

 canine there is present in the bone a third tooth about equal in size 

 to the second canine. This is manifestly a young tooth and may be 

 regarded as the third canine. . Behind this third canine are seven 

 small simple subequal molars. The dental formula of Scylacosaurus 

 would thus appear to be for the upper jaw : incisors 6, canines 3, 

 molars 7. 



The following are some of the principal measurements of the 

 specimen : — 



Greatest length of nasals 65 mm. 



Greatest length of frontals 50 



Distance between the orbits 25 



Depth of maxillary bone 33 



"Width of transverse processes of pterygoids 49 

 Length from internal nares to transverse pro- 

 cess of pterygoids 61 



Length of 6 incisors 20 



Diastema between sixth incisor and first 



canine 8'5 



Antero - posterior and transverse measure- 

 ments of second canine 8 and 6 



Distance from front of second canine to back 



of last molar 42 



