REPTILES FROil SOUTH AFRICA. 1081 



an vindulating plain whicli is geologically probably not more than 

 500 feet above the Pareiasaurus zone. The subzone is charac- 

 terised by the presence of Endothiodon uniseries Ovv., — a form 

 that at present is not known from any other part of South Africa. 

 In the Beaufort West district also occurs End,ot]tiodon. hathystoma 

 Ovv., but whether the horizon of this is above or below that of 

 E. uniseries is at present unknown. 



J^ear Beaufort West is the escarpment of the ISTieuweveld 

 which rises a few miles north of the township to a height of 3000 

 feet or more, and though it is exti-emely difficult collecting in the 

 steep slopes of shale, a number of forms of interest have been 

 collected at various horizons. 



As Dicynodon and Oudenodon occur at all levels, it might be 

 thought well to subdivide the zones by the species of Dicynodon ; 

 but there is a serious difficulty. Dicynodon is the most trouble- 

 some genus we have to deal with. Specimens differ so greatly in 

 size and shape that one hardly knows what to do unless one does 

 i\H was practically done by Owen, make every specimen the type 

 of a distinct species. For many years to come the genus 

 Dicynodon must remain in utter confusion, and will be useless for 

 sti-atigraphical work. On the other hand, the Therocephalians 

 will be as reliable guides as Ammonites and Trilobites are in the 

 marine rocks of Europe. 



In the following diagi"am are represented the horizons of the 

 Beaufort West types described in this paper, and of others whose 

 horizons are known. It must, however, be understood that the 

 heights in feet are only approximate. 



It may be well to regard the Endothiodon, zone as i-eaching 

 1600 feet above Beaufort West, and then passing into the 

 Cisteceiihalus zone. 



