382 Annals of the South African Museum. 



*<turidae. It, therefore, represents a new genus, for which I propose 

 the name Aristosaurus n. g. with the species Aristosaurus erectus n. sp. 

 Aristosaurus erectus is much more highly specialised than Thecodonto- 

 saurus, Ammosaurus, Anchisaurus and even than Massospondi/lus. 

 The build of the pelvis, and especially the position of the ischium, 

 shows adaptation to a usually bipedal mode of locomotion. The same 

 may be concluded from the far forward position of the acetabular 

 concavity in the ileum. The position, of the trochanter quartus 

 seems to be very low down on the femur. Its upper end is 41 mm. 

 from the proximal end of the bone. The length of the trochanter 

 is at least 18 nun. Therefore the lower end of the trochanter is 

 situated at more than 50 mm. from the proximal end of the bone, 

 which means very near to the middle of the femur. However, con- 

 clusions may not be drawn from this fact, because exact measure- 

 ments cannot be obtained. 



The Immerus is much shorter in relation to the body than in the 

 other Anchisauridae. The anterior extremity is also relatively t much 

 shorter in relation to the posterior one than in all other Anchisauridae 

 excepting Anchisaurus solus. As in the Plateosauridae the tibia of 

 Aristosaurus is much longer than the Immerus. This is also the 

 cast 1 in Anchisaurus solus. In the other Anchisauridae it is the reverse. 

 All this tends to show that Aristosaurus is an Anchisaurid, highly 

 specialised in the direction of the Plateosauridae, and of the bipedal 

 mode of locomotion." 



Type. In the Transvaal Museum. 



Locality. Rosendal, Senekal Dist., Orange Free State. 



Horizon. Bottom of Cave Sandstone. 



Although not specifically identifiable, the two bones in the col- 

 lection of the Rhodesian Museum, Bulawayo, which were sent me 

 for inspection by the Director of the S. Rhodesia Geological Survey, 

 should be mentioned here as they are of interest in being the only 

 known fossils from the Forest Sandstone of that region. 



One bone, from Dingaan farm, Bubi District, is the distal end of 

 a left fibula, measuring 120 mm. in length as preserved. The 

 dimensions of the distal articular surface approximate to those of 

 ThecotJonlosaurus skirtopodus (Seeley), but the bone differs from any 

 of the described fibulae of this family or of the Massospondylidae 

 or Plateosauridae in having a shaft subcircular in section, whereas 

 those of the described species are more oval in section. 



The other is a complete dorsal centrum from Waterfall farm, 

 Bubi district. It differs from that of Gyposaurus africanus (Broom) 



