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Show 1889.] OF A THERIODONT REPTILE. 573 somewhat compressed from side to side ; and the neural spines are likewise flattened, and of moderate length and height. Their terminal faces are but slightly cupped, and show a notochordal canal penetrating towards the middle of the vertebra. The transverse processes (t.p) are of moderate length, and directed backwardly as well as outwardly. These transverse processes are strengthened by three plate-like buttresses arising from the sides of the arch, and recalling the structure observed in the dorsal vertebrae of Megalosaurus. A trace of a rib-facet is observable on the anterior border of the centra of these vertebrse, which probably indicates that they belong to the earlier part of the series. The hsemal aspect has a sharp carina. Intercentra were totally wanting in this part of the spinal column. The total height of these vertebrse is 6'7 inches, the vertical diameter of the centrum being 2*4 inches. Somewhat larger trunk-vertebrse probably belong to the lumbar region, an imperfect specimen being represented from the anterior aspect in fig. 3 of the same Plate. In this specimen the centrum is very much shorter than in the dorsals, but the hsemal carina is still sharper. In the caudals, of which there are three in apposition, the centrum again lengthens, and the hsemal carina becomes less sharp. Chevrons were certainly present, but whether intercentra occurred in this region cannot be satisfactorily determined. The apparently notochordal character of these vertebrse indicates that this series of specimens does not belong to the Dieynodont suborder of the Anomodonts. Notochordal vertebrae are met with both in the Pariasaurian and Theriodont subdivisions of that order; but since the associated humerus to be immediately noticed accords with that of the Theriodonts and is quite different from the type apparently referable to the Pariasauria l, there seems every reason for regarding these specimens as referable to the Theriodontia. Turning to the bones of the appendicular skeleton, we have first to consider the scapula, of which the proximal portion of that of the right side is preserved. This specimen is represented from the dorsal aspect in Plate LV. fig. 1, on a scale of one third, with a restoration of the missing half from the scapula described by Sir R. Owen as Platy-podosaurus. The proximal portion of this bone agrees so closely in general characters with the latter specimen, as figured by its describer (Quart. Journ. Geol. Soc. vol. xxxvi. pi. xvii. fig. 1), that there is no necessity for a detailed description. It will be seen that the process marked a in the figure corresponds with that marked / in Owen's plate, while the one here marked b represents e of the latter. In regard, however, to the homology of these two processes with those of other Dieynodont scapulse, it is necessary to make a few remarks, since some confusion has arisen between the two. In his ' Catalogue of the Fossil Reptilia of South Africa,' Sir R. Owen figured, in plate lxx. fig. 1, the ventral aspect of the right scapula of a species of Dicynodon, with a portion of the precoracoid attached 1 Described by Prof. Seeley (Proc. Eoy. Soc. vol. xliv. p. 142, 1888) aa Propappus. Tbe writer will take a later opportunity of giving bis reasons for this reference. |
