346 Transactions of the Royal Societij of South Africa. 
there is a small cartilage which is not shown in the diagram ; since the 
ex-occipitals meet underneath the hinder end of BS the latter must be 
a membrane bone ; the small cartilage posterior to it must be the basi- 
occipital. BS, PS is then the para-sphenoid which is fused to the 
orbito-sphenoids (OS) and the ali-sphenoids (AS). 
Sides of the Cranium. — There is, on either side, the following bones 
from behind forwards : (1) Ex-occipital (Eo), which is large and carries 
an occipital condyle (OC) ; (2) an ali-sphenoid which bridges the 
Fig. 3. — Ventral view of skull. For explanation of lettering of Figs. 2 and 3 see text. 
space between the dorsal parietal and the ventral para-sphenoid and which 
is fused to the latter. It is, unlike that of the frog, completely ossified ; 
(3) the orbito-sphenoid (OS) which bridges the space between the dorsal 
frontal and the ventral para-sphenoid ; it is also ossified and is fused to the 
ali-sphenoid and, for a part of its length, to the para-sphenoid. 
Sense Capsules. — The sclerotic of the eye is, of course, quite free from 
the cranium. The olfactory capsules are partly calcified (the two pairs 
of calcified cartilages marked 01) and are protected by the dorsal nasals 
(Na) which are membrane bones. The auditory or otic capsules (O in 
Fig. 2) are fused to the ex-occipitals and are completely ossified. The 
