Gold-bearing Rocks of the Southern Transvaal. 135 



March 23.— W. H. Hudleston, Esq., M.A., F.R.S., 

 President, in the Chair. 



The following communications were read : — 



1. "On the Occurrence of the so-called Viverra Hastingsice of 

 Hordwell in the French Phosphorites." By R. Lydekker, Esq., 

 B.A., F.G.S. 



2. " Note on two Dinosaurian Foot-bones from the Wealden." 

 By R. Lydekker, Esq., B.A., F.G.S. 



3. " On the Microscopic Structure, and Residues insoluble in 

 Hydrochloric Acid, in the Devonian Limestone of South Devon." 

 By Edw. Wethered, Esq., F.G.S., F.C.S., F.R.M.S. 



Microscopic examination of the Devonian Limestones of South 

 Devon shows that they have been built up by calcareous organisms, 

 but that the outlines of the structure have for the most part become 

 obliterated by molecular changes, and the limestones are often ren- 

 dered crystalline. In connexion with this the author alludes to the 

 disturbances which have affected the limestones. He finds occasional 

 rhombohedra of dolomite, and discusses the probability of their deri- 

 vation from magnesian silicates contained in the rocks. 



A description of the insoluble residues follows. The micas, the 

 author considers, may be of detrital origin, but this is by no means 

 certain ; he is disposed to consider that the zircons, tourmaline, and 

 ordinary rutile were liberated by the decomposition of crystals in 

 which they were originally included. Minute crystals, referred to 

 as ' microlithic needles,' resemble ' clay-slate needles,' but are not 

 always straight : they occur in every fine residue, and as inclusions 

 in siliceous and micaceous flakes. The siliceous fragments which 

 enclose them frequently contain many liquid inclusions, which does 

 not necessarily imply any connexion between the two, though there 

 may possibly be some connexion. Micro- crystals of quartz occur, 

 and have been derived from decomposing silicates. 



April 6.— W. H. Hudleston, Esq., M.A., F.R.S., 



President, in the Chair. 



The following communications were read : — 



1. u Geology of the Gold-bearing Rocks of the Southern Trans- 

 vaal." By Walcot Gibson, Esq., F.G.S. 



The author describes the general characteristics of the rocks of 

 the Southern Transvaal, and gives a summary of previous work on 

 the area ; he then discusses the physical relations of the gold- 

 bearing conglomerates and associated rocks in the Witwatersrandt 

 district, and describes the various rocks in detail. 



He concludes that the gold-bearing conglomerates and the 

 quartzites and shales of the Witwatersrandt district (which have 

 undergone considerable metamorphism) form one series, of which 

 the base and summit are not seen ; that this series is much newer 

 than the gneisses and granites on the eroded edges of which they 

 rest, and older than the coal-bearing beds which unconformably 



