32 Annals of the South African Museum. 



The interclavicle is an elongated, truncated-triangular-shaped 

 bone about 220 mm. long and 80 mm. broad at its posterior end, 

 thin, slightly convex on its upper surface, and provided with a pro- 

 nounced ridge on its under surface. This ridge dies away distally 

 and proximally from an apex in the centre. From the ridge the 

 ventral surface slopes to left and right, and over these sloping sur- 

 faces the clavicles seem to have been able to move with a certain 

 amount of freedom. 



HUMERUS. 



Both humeri are complete and in a beautiful state of preservation. 

 The shaft is not greatly twisted, the planes of the two ends of the 

 bone lying at an angle of about 30 with each other ; but the lower 

 portion of the proximal angle is further bent until its plane makes 

 an angle of about 70 with that of the distal end. 



The greatest length of the bone is 246 mm. ; the proximal end is 

 125 mm. wide; the distal end 113 mm. wide; while the narrowest 

 part of the shaft measures 31 mm. in diameter. 



The proximal end is thickened at the articular surface, while the 

 lower twisted portion is comparatively thin. Anteriorly there is 

 a well-marked ridge running outwards from the lower end of the 

 articular surface ; this ridge can be traced along the shaft, and 

 becomes very prominent on the distal portion of the bone. The 

 articular surface of the proximal end is elongate-oval in shape, 

 widest at the middle, measuring 83 mm. in length and 38 mm. 

 at its greatest breadth. From a median longitudinal ridge it slopes 

 away on either side in a slightly convex curve. The delto-pectoral 

 ridge is not very pronounced, and there is a shallow concavity 

 above it. 



At the distal end the inner side of the bone is pierced by 

 the entepicondylar foramen, which passes from behind down- 

 wards and forwards. A well-defined groove running outwards 

 from the upper end of the foramen gives rise to two prominent 

 bounding ridges to the bone in this region, the bridge being very 

 pronounced. The foramen, which is oval in shape and has a longer 

 diameter of 21 mm., is situated 76 mm. from the distal end. 

 Another groove runs from it along the under surface, between 

 the border of the bone and the inner condylar boss. 



In general shape the hurnerus agrees with that figured by Owen 

 as " Cynodrakon major," but it differs from this chiefly in the 

 shorter and wider proximal portion which it possesses, in the 

 greater rotation of the shaft, and in the shape of the proximal 

 articular surface. 



