Extract

Plates XXXIII. and XXXIV.

Many of the nodules of the hard rock which forms the matrix of the skull of the Dicynodon tigriceps contained bones which belonged to other parts of the skeleton: some of these have been more or less relieved from their bed, and the following are amongst the best-preserved and most intelligible specimens at present exposed.

Vertebræ.—In the first part of the present Report on the Reptilian Fossils of South Africa, I briefly noticed the biconcave structure of the vertebræ of the Dicynodon, as indicating “ a more aquatic and perhaps marine theatre of life” for these ancient African Saurians, than any existing species of that order are now known to manifest in that continent. (Vide supra, p. 83.)

A vertebra (Pl. XXXIII. figs. 1–3), from the anterior part of the dorsal region, seems to belong, from the proportion which its articular surface bears to the condyle of the occiput of the Dicynodon tigriceps, to the same species, or at all events, to an individual of the same size. As it was imbedded in the same block with a skull and other bones of the Dicynodon tigriceps, it is most probably of the same species.

The centrum and neural arch are partially anchylosed, with definite traces of the suture, which is in the usual position (n). The centrum is short; the contour of the articular surface is subcircular; the margin is convex for about three lines, and then the surface sinks into a deep conical