Annals of the Transvaal Museum, 
143 
lateral border near the symphysis. The anterior border of the innominate 
is thicker than the lateral or the posterior border. There is probably a 
slight notch at the anterior end of the symphysis. 
The acetabulum is deep and large and moderately concave. It hag a 
distinct border all along its lower edge, while its upper border is only 
represented by a slight ridge on the middle of the lower end of the ilium, 
the anterior and posterior portions of the upper border not being clearly 
defined. The shape of the acetabulum indicates a horizontal femur, 
which may have been directed very slightly forward from the articulation 
surface. The foramen obturatum opened on the ventral surface slightly 
inward of the middle of the front half of the acetabular border. It is 
visible as a small process on the impression of three innominates. 
The ilium is fixed broadly to the ischio-pubis and the axis of its lower 
end rises abruptly upwards. The shaft, however, bends more outwards, 
while the upper end again resumes the original direction of the lower end. 
Excepting the broad base of the bone it is long and slender with a dis- 
tinctly narrower shaft. Its hinder border is strongly concave, while its 
front border is nearly straight, up to the base of the bone. The inner 
surface of the upper end, i.e. the articulation surface fonthe sacral rib, is 
rough. In front it is bordered by a thick ridge. Behind this ridge is a 
deep groove. It is in this groove that the ridge on the hinder border of 
the sacral rib fits. Behind this groove is a low ridge, which fits into the 
groove on the sacral rib. The surface behind this ridge, more than half 
of the whole articulation surface, is slightly hollow to accommodate the 
slightly convex part of the articulation surface of the sacral rib. 
The Hind-limb. 
The FEMUR (PI. XXII) is a long slender bone, which very much 
resembles that of Eryops. We have it represented in four specimens with 
some fragments. There are no real articulation heads, as the ends were 
covered with cartilage and are now rough surfaces. Both ends are broad 
and flat. The proximal end shows a broad and flat upper or front surface, 
which narrows down quickly towards the middle of the shaft. The front 
or inner edge of the proximal end is thin, the bone becoming thicker 
backwards or outwards. The hinder or outer border of this end is divided 
into two thin parallel ridges by a narrow groove. Towards the middle of 
the bone these ridges unite to form a thin ridge, which extends far from the 
bone along its hinder or outer side and which continues till near its distal 
extremity. This same ridge occurs on the femur of Eryops and as in 
that genus it gives the shaft of the bone a triangular section, the apex of 
which is turned backwards or outwards. 
The distal end is divided into two parts by a deep and broad groove 
on the front or inner surface. The upper portion of the articulation 
surface is smaller than the lower. The central portion between the 
articulation surfaces, which lies at the distal end of the large groove, pro- 
jects furthest, so that the articulation surfaces fall away from each other 
from this point. The lower surface provided articulation with the large 
proximal end of the tibia, while a part of the upper served for connection 
with the fibula. Therefore, in normal position the proximal end of the 
fibula would be above the proximal end of the tibia. The hinder border 
of the distal end shows a short ridge, which broadens out considerably at 
its distal end. There it unites the two articulation surfaces, lying in fact 
exactly opposite the broad front groove. Above this ridge the upper or 
front surface shows a cavity, which borders the side ridge of this surface 
