190 Reports and Proceedings — 



Plafijpodosaurus rohustiis, which have now been relieved from the 

 matrix, including the sacrum, the right " os innominatnm," and a 

 great part of the left ilium. There are five sacral vertebrae, which 

 the author believes to be the total number in Platypodosaiirus. The 

 neural canal of the last lumbar vertebra is 8 lines in diameter, and 

 of the first sacral 9 lines, diminishing to 6 lines in the fifth, and in- 

 dicating an expansion of the myelon in the sacral region, which is 

 in accordance with the great development of the hind limbs. The 

 sacral vertebrae increase in width to the third ; the fourth has the 

 widest centrum. This coalescence of the vertebrae justifies the con- 

 sideration of the mass, as in Mammalia, as one bone or " sacrum," 

 which may be regarded as approaching in shape that of the Mega- 

 therioid Mammals, although including fewer vertebras. Its length is 

 7^ inches ; its greatest breadth, at the third vertebra, 5^ inches. The 

 ilium forms the anterior and dorsal walls of the acetabulum, the 

 posterior and postero-ventral walls of which are formed by the 

 ischium and pubis. The diameter of its outlet is 3 inches, the depth 

 of the cavity 1^ inch; at its bottom is a fossa 1^ inch broad. The 

 foramen is subcircular, 1 inch in diameter. The ventral wall of the 

 pelvic outlet is chiefly formed by the pubis ; it is a plate of bone 

 6 inches broad, concave externally, convex towards the pelvic cavity. 

 The subacetabular border is 7-8 lines thick ; it shows no indication 

 of a pectineal process, or of a prominence for the support of a mar- 

 supial bone. The author remarks that of all examples of pelvic 

 structure in extinct Keptilia this departs furthest from any modifica- 

 tion known in existing types, and makes the nearest approach to the 

 Mammalian pelvis. This is shown especially by the number of eacral 

 vertebrge and their breadth, by the breadth of the iliac bones, and by 

 the extent of confluence of the expanded ischia and pubes. 



2. " On the Order Theriodontia, with a Description of a New Genus 

 and Species (^TElurosaurus felinus, Ow.)." By Prof. Owen, C.B., 

 F.R.S., F.G.S. 



The new form of Theriodont reptile described by the author in this 

 paper under the name of JElurosatirus felinus is represented by a skull 

 with the lower jaw, obtained by Mr. Thomas Bain from the Trias of 

 Gough, in the Karoo district of South Africa. The postorbital part 

 is broken away. The animal is mononarial ; the alveolar border of 

 the upper jaw is slightly sinuous, concave above the incisors, convex 

 above the canines and molars, and then straight to beneath the orbits. 

 The alveolar border of the mandible is concealed by the overlapping 

 teeth of the upper jaw; its symphsis is deep, slanting backward, 

 and destitute of any trace of suture ; the length of the mandible is 

 31 inches, which was probably the length of the skull. The incisors 

 are |rt, and the molars probably gzf or gzB. all more or less laniariform. 

 The length of the exserted crown of the upper canine is 12 milliras. ; 

 the root of the left upper canine was found to be twice this length, 

 extending upwards and backwards, slightly expanded, and then a 

 little narrowed to the open end of the pulp-caviry. There is no 

 trace of a successional canine ; but the condition of the pulp-cavity 

 and petrified pulp would seem to indicate renewal of the working 



