244 Prof. Owen on the Reptilian Fossils of South Africa. 



wrought out clearly and without fracture to the more slightly and normally 

 expanded ends above described and shown in fig. 6. 



The second of the vertebrae in fig. 5 shows by the termination of its centrum 

 that it was not the last sacral vertebra ; whence it is to be inferred that the number 

 of those in the Dicynodon exceeded two ; whilst the close correspondence between 

 the bodies, and especially between the peculiarly shaped neural spines of the two 

 sets of sacral vertebrse (figs. 5 & 6), leads me to the conclusion that they are anterior 

 and posterior parts of the same sacrum, or of the sacrum of the same species. 

 They were, however, wrought out of different fragments of the matrix, and cannot 

 be made to fit ; so that there may be more than four vertebrse in the sacrum of 

 the Dicynodon. 



In the series of bones appertaining, to judge by their size and associated locahty, 

 to the Dicynodon tigriceps, are two belonging to the arches that have supported 

 the fore and hind limbs. 



One of these (PI. XXXIV^. fig. 2, s, g) is a single, broad, and flat bone, with part of 

 the cavity for the head of the proximal long bone of the hmb, showing at the lower 

 half of its circumference an elongated rough surface, apparently for synchondrosis 

 with the other elements of the arch contributing to complete that cavity : on one side 

 of the more expanded part of the bone is an extensive rough surface (figs.2&3, x , x x ) 

 apparently for similar ligamentous junction with another part of the skeleton. The 

 other bone (fig. 1 ) exhibits the entire cavity for the proximal bone of its limb, and 

 is obviously composed of the vertebral (or pleural) and sternal (or haemal) elements 

 of the arch anchylosed where they constitute that articular cavity, traces of the 

 obliterated suture being there discernible. 



According to the analogy of the Reptilia, the longer and narrower of the two 

 constituents of the last-cited arch should be the pleural one, the broader and 

 shorter the hsemal element ; and this latter likewise exhibits a foramen (o) near the 

 articular cavity which may either be interpreted as an ' obturator foramen,' or an 

 homologue of the foramen which is found in the coracoid of the Crocodiles, of the 

 Monitors [Varanus), and of many other Reptiles, recent and fossil. 



Pelvic arch. — The bone represented in figure 1, PI. XXXIV., resembles in its 

 general proportions the coracoid of the Megalosaurus. The anchylosed condition 

 of the two parts of the arch where they form the articular cup in fig. 1. PI. XXXIV. 

 renders it most probable, however, that they belong to the pelvis, and I, pro- 

 visionally, regard them as the left ' os innominatum ' of the Dicynodon. The 

 pleural element or ' iHum ' {a, b, c) is an inequilateral triangular plate of bone, 

 with the lower angle thickened and expanded, especially externally, to form the 

 upper half of the acetabulum. Its anterior border (a, b) is the longest, nearly 



