ANOMOUOXT REPTILES. 361 



probably seven denticulations, and in the 3i-d, five. As Trojndo- 

 stoma approaches the adult condition the molars seem to be 

 gradually lost. Some specimens show only three, others but two 

 or one, and in old age all trace of even the sockets disappears. 



In those specimens which are regarded as males there is a 

 pair of powerful tusks. In the supposed females, in place of the 

 tusks are, as in " Oudenoclon" caniniform processes. One 

 specimen (E,871) is remarkable for having on the right side a 

 well-developed tusk, and on the left side no trace whatever of a 

 tusk. This specimen is probably the oldest animal of the series, 

 and I regard it as a female which has developed a tusk on the 

 one side. 



The septomaxilla lies within the nostril forming its lower wall. 



The lacrimal extends forwards between the nasal and the 

 maxilla, and n)eets the septomaxilla. 



The relationships of the bones of the top of the skull will 

 best be understood from the diagram I have given. The greater 

 part of the figure is drawn from specimen R 860-, but the anterior 

 and posterior portions are from two other specimens. Nearly 

 every suture is confirmed by more than one specimen. 



The most noteworthy features of the upper side of the skull 

 are the presence of thickened bosses on the nasals, and the 

 development of the postorbitals and parietals into a pair of lateral 

 crests with a deep groove between them. 



The palate has already been figured by Lydekker ; but as I 

 think he is in error in a number of points, and as the whole 

 structure of the antei'ior palatal region is exceedingly well shown 

 in specimen R 860, I think it worthy of being figured again. 

 The great size of the palatal portion of the premaxilla is seen and 

 the relations of the palatine, transpalatine, and pterygoid bones 

 to each other. The prevomer has its lower border developed ai8 

 a pair of plates. In this Tropidostoma differs from Dicynodon^ 

 and agrees with Endothiodon and Emydorhynchua . 



The occiput has been figured and described by )Seeley. 



