Extract

Plates XXIX. to XXXII.

Of the extinct Reptilia hitherto discovered in different regions of the globe, the fossil skulls of some species have exhibited combinations of characters now pecu­liar to distinct orders of the class, or even to distinct classes of Vertebrate animals. The Ichthyosaurus, for example, shows the piscine proportions of the premaxillaries in the upper jaw : the Rynchosaurus shows the chelonian absence of teeth in both jaws : but the Dicynodon seems to have borrowed its peculiarities from a higher class, and to have engrafted some mammalian characteristics upon the upper jaw, whilst it combined a chelonian edentulous under jaw, and a crocodilian occiput, with a cranium essentially constructed after the lacertian type.

These and most of the minor peculiarities of the cranial organization of the Dicynodont reptiles have been pointed out in my former account of some of the smaller species of the genus*. There were, however, in Mr. Bain’s first collection some fragments indicative of a Dicynodon, with subcompressed tusks (D. Bainii), as large as a Walrus, but these were too scanty to deserve more than a reference to their indication of the size to which some species of that peculiar genus of reptile had attained during the mesozoic period in South Africa.

In a subsequent transmission of fossils from the Graaf Reinet district and Kafraria by Mr. Bain, two almost entire skulls of a still larger species of Dicynodon with circular tusks were included. They have been ably relieved from their extremely hard matrix