On Ictidosuchus Primevus. 181 
posterior and a sharp anterior border. As it passes upwards it 
gradually widens, and becomes at its upper end almost quite flat. 
The lower end of the scapula is unusually broad, and, with the 
exception of the low ridge which passes up from the glenoid cavity, 
almost quite flat. The lower border of this large anterior flat expan- 
sion articulates with the precoracoid. The acromion process is quite 
rudimentary. The glenoid surface of the scapula is of moderate 
size. 
The coracoid is very similar to the coracoid in the Anomodonts, 
but has a rather larger glenoid cavity, and the posterior part is rather 
more developed. 
The precoracoid differs considerably from that of the Anomodonts. 
It is a larger element proportionally than in the Dicynodont girdle, 
being very considerably larger than the coracoid. In its upper and 
posterior quarter there is a large oval foramen, which is completely 
formed by the precoracoid. 
On the whole the shoulder girdle, so far as known, seems to be of 
a more primitive type than that of either the Anomodont or the 
higher Theriodont. In Cynognathus the scapula is much specialised, 
having a well-developed spine and a distinct acromion which pro- 
jects outwards considerably from the general surface, and the pre- 
coracoid foramen is almost, but probably not altogether, surrounded 
by the precoracoid bone. In the Dicynodont type there is likewise 
a well-developed acromion ; while the precoracoid foramen is in the 
upper border of the precoracoid and partly walled by the scapula. 
In the Russian genus Rhopalodon the scapula is moderately flat, and 
the acromion rudimentary as in Ictidosuchus, while there is a further 
agreement in the large development of the precoracoid and in the 
foramen being entirely in the precoracoid bone. 
HuUMERUS. 
The humerus is fairly well preserved, though unfortunately the 
distal extremity is missing. It is rather a slender, elongated bone, 
and is unlike the humerus of any form hitherto described except the 
imperfectly known humerus of Theriodesmus. Unfortunately in 
Theriodesmus the humerus is only known from a mould of the upper 
and lower ends, and so imperfect are the impressions that Seeley * 
was originally led to the conclusion that the remains were those of a 
mammal, though he { afterwards recognised them to belong to a 
* H. G. Seeley, ‘‘ On Parts of the Skeleton of a Mammal from Triassic Rocks, 
&c.,” Phil. Trans., 1888, p. 141. 
+ H. G. Seeley, ‘‘The Reputed Mammals from the Karroo Formation of Cape 
Colony,’’ Phil, Trans., 1895, p. 1019. 
