1917.] The Fourth Indian Science Congress. cciii 



of tourmaline introduced by pneumatolitic processes from the intrusive 

 granite. The author also gives other arguments illustrating the mag- 

 matie segregation theory — pegmatitic or aplitic— - of the formation of the 

 lodes, as contrasted with the theory of BJeeck of their formation by mineral 

 solutions and pneumatolysis. In the case of the wolfram and cassiterite 

 quartz veins, of which the pegmatitic origin is not so clear, it seems 

 reasonable to regard them as a hydro- thermal phase of pegmatites. 



A Revised Classification of the Gondwana System. — By 



G. de P Cotter. 



An attempt is made in this paper to sub-divide the Gondwana System 

 into series and stages on the lines laid down by the International Con- 

 gress of Geology, and to determine the European equivalents of each 

 stage. The Maleri stage has been separated from the Kota stage ; the 

 former has been placed in the Trias, while the latter remains in the 

 Oolitic. Evidence is brought forward to show that the Panchet stage of 

 Raniganj is lower Trias. The upper Trias is represented by the Maleri 

 stage, and the Rhaetic by the Thinnfeldia odontopteroides beds of South 

 Rewah, to which a new stage name, the Parsora stage, is given. The 

 Damuda series are shown to be Permian, and not partly Trias, as Koken 

 supposed. The relationships of the Maleri to the Parsora stage are doubt- 

 ful ; the author paid a visit to South Rewah to determine which was 

 tratigraphically above the other, but no definite conclusion was arrived 

 at. He suggests, however, that the Parsora stage is very possibly the 

 upper of the two. The Umia stage is no longer placed in the upper Jurassic , 

 but in the lower Cretaceous, in accordance with the work of Kitchen. 



An account of the Sub-division of the Deccan Trap Series in 

 the neighbourhood of Xarayanganj. Mandala District. 

 Central Provinces. — By K. A. K. Hallo wes. 



The author, in continuation of the work of Fermor and Fox in the 

 Chhindwara District, gives a short account of his sub-division of the 

 Deccan Traps in Mandla District. The separation of the boundaries of 

 particular flows was principally effected by the aid of vesicular surfaces, 

 green-earth horizons, intertrappean limestone and chert and by the 

 terraces due to the above. Eight different flows have thus been distin- 

 guished, which also are found to possess minor differences of texture and 

 composition ; all of them being either basalts or dolerites with varying 

 amounts of olivine, serpentine, chlorophaeite and palagonite in addition 

 to the ordinary minerals of the Deccan Trap. He discusses the origin of 

 some of the palagonite, the varying specific gravities of the flows, their 

 silica content and their other physical characteristics. 



On the application of Cochineal Stain on Calcite, and Arago- 



nite. — By S. Datta. 



The author details a further set of experiments in continuation of 

 those described bv him in a paper before the Indian Association for the 

 Cultivation of Science in September 1916, on the staining of these same 

 minerals by means of aniline black, as a means of distinguishing them. 



On the Occurrence of Limburgite in British Baluchistan.— By 



H. Das Gtjpta. 



The author describes a limburgite from the Deccan Trap of Baluchis- 

 tan, characterised by a smaller amount of the phenocryste of olivine as 



