D. M. S. Watson—The Beaufort Beds, S. Africa. 203 



EXPLANATION OF PLATE XV. 

 Steganohlastus ottawaensis. 



Fig. 1. Specimen A, from the posterior interradius, showing periproctcals and, 



above them, the supposed hydropore. 

 ,, 2. Specimen B, from the posterior interradius, showing the same 



features. 

 ,, 3. Specimen A, the lip of the anterior subvective groove, showing pores, 



adradial suture, and spine-pits. For exigencies of lighting, the 



perradius is sloped downwards from right to left. x 5 diam. 

 ,, 4. Specimen A, from the right anterior interradius. 

 ,, 5. Specimen B, adoral view ; compare Text-fig. 5. 

 ,, 6. Specimen A, adapical view. 

 ,, 7. Specimen A, adoral view ; compare Text-fig. 6. 



All the figures are from photographs by Mr. H. G. Herring, and all, except 

 Fig. 3, are enlarged 3 diameters. 



The Text-figures are based on pencil drawings by Mr. G. T. Gwilliam. 



II. — The Zones of the Beaufort Beds of the Karroo System is 



South Africa. 



By D. M. S. Watson, M.Sc, Lecturer in Vertebrate Palaeontology in University 

 College, London. 



PROFESSOR H. G. Seeley, in his well-known paper on Panasat(rus 

 Baini, incidentally mentioned that the Beaufort Beds, in which 

 it was found, could be divided up into zones on the evidence of the 

 reptiles they contained. Dr. R. Broom, following out this suggestion, 

 went further and divided them into the 



Cynognathus 



Procolophon 



Lystrosaurus \ „ 

 /-,•/,• J , ,- Zones. 

 Cisticephaius | 



Endothiodon I 



Pariasaurus ^ 



This division is perfectly correct and cannot at present be improved 

 upon, but beyond saying to which zone all the species which he 

 recognized as distinct belong. Broom has never offered any evidence in 

 support of it or indeed explained the real meaning of the division. 



iJuring my visit to South Africa I had the good fortune to collect 

 from all these zones, and propose in this short paper to explain the 

 evidence I collected and then to show that from the evidence of 

 specimens in museums it is possible to construct a map which is self- 

 consistent. 



The three lowest zones are best seen round Beaufort West. 

 Beaufort West stands on the ]£ndothiodon zone, and to the south 

 there is a great expanse of slightly rolling country, the Gouph, which 

 is obviously composed of rocks lying below those on which the town 

 is built. To the north the magniticent escarpment of the Nieuveld 

 rises about 3,000 feet above the plain. 



The beds which form the Grouph have been very extensively 

 collected from by T, Bain, H. G. Seeley, The Survey, R. Broom, 

 J. H. Whaits, and the author. They yield several species of 

 Pariasaurs, none of which have an armour more extensive than 



