304 Transactions of the Royal Society of South Africa. 
overhanging the fenestra. This eave is deeply notched on its anterior edge. 
The inner border of the notch is formed by the posterior end of the epiptery- 
goid, the remainder of the border by the pro-otic. This notch must represent 
the pterygo-paroccipital foramen of Diademodon, the retraction of the 
epipterygoid from the quadrate giving rise to the open form. The foramen 
for the exit of the Vllth nerve is larger and nearer the pituitary fossa than 
in Diademodon. 
The periotic (pro-otic) forms most of the side wall of the brain-case 
behind the dorsum sellse, articulating behind with the fused exoccipital 
and supraoccipital, the latter forming the posterior wall of the canal for the 
IXth-XIth nerves. 
The paroccipital process is quadrangular in section, and not triangular 
as in Diademodon. 
Quadrate. — Another feature of interest lies in the quadrate mass. The 
quadrate is a plate of bone with a slightly hollowed anterior surface, and 
lies on the anterior face of the squamosal, being furnished with an outer 
flange which is clasped by the squamosal. It has no pterygoid wing. The 
quadrato-jugal is lateral to the quadrate. It is bifid in character, consisting 
of a larger anterior vertical thin plate and a smaller posterior one which 
clasp the lower edge of the squamosal between them. There is probably 
a quadrate foramen between the quadrate and the quadrato-jugal. A 
somewhat similar quadrate complex exists in Protacmon, but there the 
quadrato-jugal spreads inwards between the quadrate and squamosal. 
Discussion of the relationship of this type to other Cynodonts is deferred 
until a more complete account of the fossils of the Upper Beaufort Beds is 
prepared. It is sufficient here to point to some of the advanced features 
which this form possesses — the complete loss of the quadrate ramus of the 
pterygoid, the gap between the quadrate and the epipterygoid, loss of a 
pterygoid process separating the palatine and vomer, and extreme flattening 
of the basicranium — all logical results from the evolutionary tendencies 
traced in the Theriodontia, as pointed out recently by Watson. 
The absence of an intern asal process of the premaxilla and the usurpation 
of the functions of prevomers by palatine processes of the premaxillse — 
functioning as supports to Jacobson's cartilage — are interesting features 
which are distinctly mammalian in character. The former is paralleled 
in a large skull of Cynognathus from Winnaarsbaaken, Albert District, now 
in the South African Museum, in which the premaxillse form a pillar in front 
of the nostrils reaching upwards and backwards to the nasals. 
