414 Prof. H. G. Seeley on Hortalotarsus skirtopodus. 



well ossified and well rounded from back to front, and concave 

 on the hinder margin in the usual way between the condyles, 

 though the right condyle is not preserved. 



The tibia and fibula are in natural association, but the 

 proximal articular end of the fibula is lost, and the proximal 

 end of the tibia is slightly broken. Both bones have large 

 central cavities, like Palceosaurus and the allied Triassic 

 reptiles of Europe. 



The tibia (fig. 2) is 7 T 7 g- inches long. The transverse width 

 of its distal end is 1^ inch. The width at the proximal end is 

 1 T V inch as preserved, but may have been slightly more. The 

 antero-posterior measurement at the proximal end is 2^ inches 

 and at the distal end is -fa inch. Thus the two ends of the 

 bone have the aspect of being twisted nearly at right angles 

 to each other, as in many other Dinosaurs. In general form 

 and size the bone resembles Agrosaurus, and, in a less degree, 

 Palceosaurus. 



The proximal articular surface is flat, truncate, slightly 

 inclined backward and slightly inclined outward. It appears 

 to have been subtriangular, wide behind, with a slight notch 

 between the condyloid eminences on the posterior surface. 

 The internal contour of the articulation was rounded from 

 behind forward to the cnemial crest, which is small, rounded 

 in front, and defined by a slight shallow fibular groove placed 

 anteriorly, posterior to which was the large condyle on the 

 external or fibular side. 



Seen from the internal aspect the anterior vertical contour 

 of the bone is nearly straight, being very slightly concave ; 

 but the posterior contour is concave in its proximal third, 

 owing to the backward extension of the condyles, and then 

 straight almost to the distal end ; the bone has an aspect of 

 being compressed from front to back in the lower part of the 

 shaft. If there is an appearance of slight distal expansion, it 

 is due to the way in which the metatarsal bones are crushed 

 upon the tibia in front. On the posterior aspect the shaft 

 contracts above the middle length to about T 6 ,j inch. It is 

 well rounded from side to side in the middle, but flatter 

 towards the distal end. Both inner and outer contours are 

 concave in length, but the concavity at the distal end is only 

 marked on the fibular side. This is due partly to crushing 

 and partly to extension of the bone towards the fibula. 

 If there is any notch on the distal fibular border of the tibia 

 it is not exposed. There does not appear to be any notch or 

 groove on the anterior side at the distal end, the condition of 

 the bone in this respect resembling the tibia of Euskelesaurus. 

 The absence of the distal notch on the tibia is a distinction 

 from all known allies in the Trias of Europe. 



