Fo.'tsil Amjjhihian. 179 



large animal. Till recently, however, the remains have been too 

 •fragmentary to warrant description. But a few months ago one 

 of my students, Mr. R. A. Albertyn, obtained near Rouxvillo, 

 O.R.C., a large number of fragments of the skull of what is per- 

 haps the same Lahyrinthndont as occurs at Aliwal North and 

 Burghersdorp. The fragments only represent about a third of the 

 upper surface of the skull, and it has been found impossible to fit 

 all of them together, still as it has been possible to reconstruct the 

 greater part of the right orbital and temporal regions and the left 

 prefrontal and frontal bones, a very fair idea is obtained of the 

 structure of the skull, and it becomes manifest that the animal is a 

 species of Cyclotosaurus. 



The orbit measures 60 mm. in length and J 6 mm. in breadth. 

 Externally about 18 mm. of the margin are formed by the jugal 

 bone, while the whole of the anterior border is formed by the 

 prefrontal bone. The frontal bone is almost excluded from the 

 orbit, but the external corner of the frontal just separates the pre- 

 frontal from the postfrontal. The postfrontal forms the 

 whole of the inner, and posterior margin of the orbit to the 

 middle line of the orbit behind, where it meets the postorbita!. 

 It is thus seen that the orbit is almost exactly similar in structure 

 to that in Cyclotosaurus rohustus, the only difference being that 

 the frontal scarcely forms any part of the orbital margin. 



The frontal bone is relatively narrower and the prefrontal 

 wider than in C. rohustus, the former being 50 mm. wide, and the 

 latter about 90 mm. 



From the back of the orbit to the front of the auditory notch 

 is 95 mm. 



The postorbital bone is relatively considerably larger, and the 

 squamosal, though imperfect, apparently smaller than in C. rohus- 

 tus. Anteroposterior length of the postorbital is al)out 85 mm. 



The auditory notch, though imperfect behind, has apparently 

 been closed. Its greatest transverse measurement is 48 mm., and 

 the anteroposterior measurement was probably about the same. 

 From, the anterior border of the auditory foramen to the nearest 

 point of the back margin of the skull is about 90 mm. 



If the anterior part of the skull bears the same proportion to 

 the hind part in C rohustus, and it is possible from the larger 

 size of the prefrontal that the anterior part maj' be relatively even 

 larger in the S. African form, then the whole skull was, not im- 

 probably, from 650 to 700 mm. in length. 



