190 Annals of the South African Museum. 



the prevomer, the palatine, and the premaxilla each plays a small 

 part in the formation of its border, it is mainly surrounded by the 

 premaxilla. It is very large, the size being its most striking feature. 

 It leads directly up into the nasal cavity. A section across the 

 snout of the co-type shows that the nostril is divided into two 

 unequal parts by a nearly horizontal turbinal, probably formed 

 by a process of the septomaxilla. The upper portion is very 

 much larger than the lower, whose floor is concave with a slight 

 median ridge formed along the junction of the dorsal surfaces 

 of the two premaxillary bones. The evidence seems to connect 

 the lower portion with the anterior vacuity of the palate, while 

 the upper part the true nostril is connected by a more gradually 

 sloping tube with what has been identified as the internal narial 

 opening. 



Hitherto, the anterior palatine vacuity has been observed in 

 very few Therapsids, and never to the extent displayed here. 

 Broom (1911) mentioned its occurrence in Gomphognathus, and says 

 ' In the anterior palatine vacuity there is a pair of narrow bones 

 showing what I suggested a good many years ago were probably 

 prevomers." Here the opening seems to have been a single 

 median one ; its size is not mentioned, and it is not figured. The 

 same author (1914) has figured a pair of openings surrounded by 

 the premaxillae in Lycochampsa ferox. These two forms are both 

 ( Vnognathids, and the vacuity does not seem to have been recorded 

 in any of the Therocephalia or Gorgonopsia. 



Another interesting feature concerns itself with the vomer. In 

 Diademodon there is a large median vomer lying between the 

 pterygoids and palatines. Watson considers that in Gorgonops 

 there is a large mammalian vomer in the posterior part of the 

 palate as in Diademodon and a pair of fused prevomers anteriorly. 

 In the Therocephalian Scymnosaurus ivatsoni (described by Watson 

 as Lycosuchus sp.) there is a narrow vomer lying in the same position 

 as in Gorgonops, and a pair of prevomers anteriorly. In Scylaco- 

 saurus sdateri there is no median vomer on the palate. From 

 the general features of the skull under discussion one would expect 

 to find in it some trace of a posterior vomer on the palate. I can, 

 however, find no trace of sutures where such a bone is likely to 

 occur, and, moreover, the pterygoids are seen to be separated 

 from one another almost throughout their length by a median 

 longitudinal suture. On the other hand, the bone separating the 

 premaxilla from the pterygoids is a single bone, as in Dicynodon. 



