the S'/im// <y Diadoinodoii. 313 



aooiiratc, examination of it in tlic light of tlic new sknll 

 which 1 have described above shous some new Features : — 



1. A septo-maxilhirv is {)Uiinly seen in the left nostril; it 

 has been largely chiselled away on the right side. It forms 

 a small part of the border of the back of the anterior nares, 

 being wedged in between the premaxilla and the nasal. 

 It has an anterior ])rocess which runs along on the pre- 

 maxilla, funning a narrow floor to the nostril. The bone 

 bears a small knob, which suggests a hoiizontal division of 

 the nostril. 



2. The transpalatine is very plainly seen, the sutures 

 separating it from otiier bones, although close, being in- 

 filtrated with red. It occupies the same position as iu the 

 .Diadeniodun skull and has the same relations, but has a 

 rather larger palatal extension. 



3. The left quadrate is well shown (fig. 8) ; it agrees 

 closely with that described above, but has preserved a long, 

 slender, inwardly directed process which is tightly applied to 

 the inner and posterior face of the posterior ramus of the 

 pterygoid. The relationship of this process to tlie pterygoid 

 is the exact reverse of that which obtains in Sphenodon and 

 other primitive Diapsids. 



4. The side of the brain-case is fairly well shown and 

 agrees exactly with that described above. 



5. The continuity of the dorsal ridges of the vomer and 

 anterior part of the basisphenoid, which was not quite 

 established by the skull already described, seems to be 

 demonstrated by this specimen. 



Diademodon sp. 



R. 3605 is the imperfect anterior part of a Diademodon 

 skull which was cut into slabs by Prof. Seeley. 



It shows excellently the teeth and the relations of some of 

 the bones of the palate. 



In the region immediately behind the secondary palate 

 the palatines are clearly seen as thin vertical plates tightly 

 adpressed to the inner sides of the alveolar parts of the 

 maxillse. The vomer is displaced but still remains attached 

 to the left palatine ; it is high up in the skull, well above the 

 level of the bottom of the narial passage. As it is traced 

 forward it keeps this elevation until it finally disappears. 

 In this region the secondary plates of the palatines come 

 close together and meet. In this same region also begins a 

 single median bone of oval section, much higher than wide. 

 This bone can be traced forward, lying just dorsal to the 



