The ancestry of the Theromorpha themselves is also shrouded in mystery. Attempts have been made to connect them with the Permian _Protorosaurus_, _Palaeohatteria_, and _Eryops_. On the other hand, some retain various Stegocephalous reminiscences (_e.g._ the roofed-in condition of the skull by membrane-bones, amongst which, besides others, supratemporals and postorbitals can be recognised; occurrence of cleithra in _Pareiasaurus_; distinct epiotic bones in _Elginia_). Although they have died out as a group, they have perhaps given rise to several side-branches, one of which (leaving aside the question of Mammalian origin) seems to have flourished as the Dinosauria. We divide the Theromorpha into four orders, which are, however, liable to run into each other, and it is reasonably to be hoped that many forms may be discovered which will connect not only these provisional orders with each other, but also with other sub-classes. ORDER I. PAREIASAURI Cranium completely roofed in by membrane-bones. The only foramina are the nostrils, orbits, and the interparietal foramen. The teeth are comparatively small, and stand in even series in both jaws. _Pareiasaurus_, several species from the Karroo sandstone of South Africa. _P. baini_ was an extremely clumsy brute, of most uncouth appearance, standing between 2 and 3 feet high, and measuring with the short tail nearly 8 feet in length. The skull is very massive, 18 inches long and slightly broader, with a rugose, deeply pitted surface. The teeth are thickly enamelled, serrated at the margin, with many pointed cusps; those {305}of the vomer, palatines, and pterygoids are recurved and arranged in several longitudinal rows. There is a small incisive foramen in the premaxilla; the choanae lie within the pterygoids. The palate has a pair of large lateral vacuities. Between the squamosal and quadrate is a small foramen, as in _Belodon_ and _Sphenodon_. The nares are terminal, bordered behind by the nasals, and divided by the premaxillaries. The occipital condyle is a single knob, but the lateral occipital bones also partake in its formation. The shoulder-girdle is strong. The scapula slants backwards, is broad, and possesses a longitudinal spine, an almost exclusively Mammalian character. The scapula, coracoid and precoracoid are fused together, and are united ventrally with those of the other side. There is a T-shaped interclavicle, a pair of clavicles, and a pair of slender, long cleithra, which extend along the upper anterior margin of the scapulae. The humerus possesses enormous crests. The broad ilium is attached to two, or perhaps three, sacral ribs. The acetabulum is closed. The pubes and ischia are united into one broad mass of bone, and the obturator-foramina seem to be just large enough to permit of the passage of the nerve. Both fore- and hind-limbs are plantigrade and five-toed. The tibia articulates with one large bone, which is supposed to represent the united astragalus and