324 C. A. SUSSMILCH AND T. W. E. DAVID. 



The occurrence of Mesosaurusin the Dvvyka shales over- 

 lying the tillites seems extraordinary, in view of the fact 

 that elsewhere it is found in strata of Upper Permian 

 (Zechstein) Age, as in Brazil, unless in South Africa also 

 its age is Permian. In regard to Mesosaurus, R. Broom 

 states : — 



" Whatever be its affinities, it is agreed by all to be a true 

 reptile, and one which has undergone considerable specialisation. 

 As in no part of the world has any reptile ever been discovered in 

 beds earlier than Permian, we seem justified in concluding that 

 the Upper Dwyka shales are not older than Lower Permian. 

 Mesosaurus is of further interest in that an almost identical form 

 occurs in Brazil." 



The Ecca series which overlies the tillites contains 

 Lepidodendron pedroanum a form which links it up with 

 the Tuburao Beds of Southern Brazil. 



The Lower Beaufort series, which overlies the Ecca 

 series, is obviously the equivalent of the Dwina series of 

 Russia, as it contains the lamellibranchs Palceomutela 

 and Palceanodonta, and Pareiasaurus among its numerous 

 reptiles, together with Glossopteris and Schizoneura. The 

 age of the Lower Beaufort series appears to be Zechstein, 

 so that the age of the Ecca series and such parts of the 

 Dwyka shales as contain Mesosaurus can be provisionally 

 considered to be Lower Permian, or possibly Artinskian. 



The Eurydesma globosum beds of South West Africa so 

 closely associated with the Dwyka tillites are probably 

 homotaxial with the Salt Range boulder beds of India, and 

 the Eurydesma cordatum glacial horizon of the Hunter 

 District in New South Wales, the Irwin River of West 

 Australia, the Wynyard Beds of Tasmania, the Bacchus 

 Marsh Beds of Victoria, the Hallett's Cove and Inman 

 glacial beds of South Australia. Their age may tentatively 

 be considered to be Uralian. 



