122 
Annals of the Transvaal Museum 
f 
5 -5 cm. above the lower border. It is a round opening of about 9 mm. dia- 
meter. The foramen passes obliquely through the bone, upwards, backwards 
and inwards. 
Humerus. 
Both humeri have been preserved, but both have suffered much from 
pressure. The proximal plate of the right humerus has been flattened and 
broadened, while the plate of the left one has been compressed. The shaft of 
the right humerus has been twisted. 
The length of the humerus is 20-5 cm. in the left (PI. XVII, figs. 2 and 3) 
and 21-5 cm. in the right bone. The broad surfaces of the distal end of the 
humerus make an angle with those of the proximal plate. The thick medial 
border of the proximal plate is concave. The caput humeri is not situated at 
the extreme end of the medial border, but it lies more inwards on the upper 
border, of which it forms the highest point. From here the upper border runs 
outwards and downwards to the lateral side. The fossa bicipitis lies below 
this border and is bounded medially by the thick medial edge and laterally 
by the convexity of the crista radialis. It does not pass on to the shaft. The 
crista radialis projects from the lower endTrf, the lateral side of the plate. 
Its height is about o-6 cm., and its length about 5 cm. The upper end of the 
crista stands out from the rest of the lateral border towards the medial side 
and consequently the medial surface of the crista and a portion of the plate 
near it is convex. The posterior surface of the plate is convex, except the 
portion medial to the caput humeri, which is concave, and the posterior 
surface of the crista, which is also concave. There is a circular depression on 
the posterior surface inwards of and slightly above the lower end of the crista. 
This cavity is not accidental, for it is present in the same position in both 
bones (fig. 2 of PI. XVII shows it plainly). The lower end of the crista radialis 
lies at a distance of 11 cm. from the distal end of the condylus lateralis. The 
distance between the upper end of the crista and the medial upper corner of 
the bone is 10 cm. in the left bone and is nearly 12*5 cm. in the right one. It 
seems as if the dimensions of the left bone are nearer to the original. 
The breadth of the shaft at its narrowest place is 2-5 cm. Its thickness 
there is 3-3 cm. (left bone). The breadth of the distal end is 7-4 cm. in the 
left and 7 cm. in the right 
bone. The distal end of 
both bones (text-fig. 22) 
is flattened and therefore 
broader than originally. 
A rounded ridge runs from 
the lower end of the crista 
radialis right to the distal 
edge of the condylus later- 
alis. A broad, low ridge 
passes from the condylus Text-fig. 22. Massospondylus Bvowni. Left humerus. 
medialis upwards on the O ut ! ine ? f dist ^ ® nd . seen from below - Anterior 
, f. border above. Nat. size, 
shaft and disappears near 
the middle of the bone. Between these two ridges the anterior surface of 
the distal end is strongly concave. This concavity becomes narrower and 
shallower upwards and disappears in the middle of the shaft. The posterior 
surface of the distal end is concave along its middle, but it seems that this 
concavity is at least greatly exaggerated by pressure. The condyles are not 
produced backwards and they stand out slightly anteriorly. The articulation 
